MediaLab Blood Bank
What bacterial organisms have been linked to platelets stored at 20-24 oC?
Gram positive and gram negative organisms have been linked to platelets stored at 20-24 oC. These organisms include the bacteria Escherichia coli, Enterobacter species, and Streptococcus species.
Which blood group is most frequently associated with Cold Agglutinin Disease (CAD)? Kell Kidd Duffy I
I Kell is a warm antibody and does not activate complement. Kidd can bind complement but is not activated at colder temperatures. Duffy is a warm antibody and does not activate complement.
Newborn ABO typing
Most laboratories will not do reverse testing on newborn samples because newborns do not produce ABO antibodies until 4 to 6 months and any antibodies present are likely to be of maternal origin.
When administering fresh frozen plasma (FFP), which one of the following is considered standard blood bank practice? Should be ABO compatible with the recipient's red blood cells Must be the same Rh type as the recipient Is appropriate for use as a volume expander Component should remain frozen when it is issued
Must be the same Rh type as the recipient FFP should be ABO-compatible with the recipient's red blood cells, but does not need to be the same Rh type as the recipient because it is a cell-free product. FFP should not be used as a volume expander; preferably, use a safer product such as serum albumin. This limits the exposure to transfusion-transmitted diseases and lowers the risk of transfusion reactions. FFP is indicated for patients that are actively bleeding or to treat clotting factor deficiencies. It may be used as a replacement fluid during plasma exchange procedures. FFP must be thawed prior to being issued for transfusion purposes.
Which of the following is the proper storage temperature for fresh frozen plasma (FFP)? 37 degrees Celsius 4 degrees Celsius - 20 degrees Celsius - 10 degrees Celsius
- 20 degrees Celsius
From the IgG molecule illustration, which region is the heavy chain? A B C D NEED IMAGE
A = Heavy chain B = Light chain C = Antigen binding site D = Variable region
What is considered a high-incidence antigen?
A high-incidence antigen is one that appears in 98% or more of the population.
When processing umbilical cord blood samples for hematopoietic progenitor cells (HPC), what tests are performed on both the mother's blood and cord blood? ABO & Rh HIV-1 & HIV-2 HBV & HCV HTLV-I & HTLV-II
ABO & Rh Umbilical cord blood requires special processing. Both the mother's blood sample and the cord blood are tested for ABO and Rh. The maternal sample will have an antibody screen performed along with testing for HIV-1 & HIV-2, HBV & HCV, and HTLV-I & HTLV-II. Also, HBsAg, anti-HBc, and syphilis status is determined. The cord blood is cultured for cytomegalovirus.
A false-negative reaction while performing the DAT technique may be the result of: Red cell/AHG tube is over centrifuged Blood collected in tube containing silicone gel Saline used for wash stored in glass or metal container AHG addition delayed for 40 or more minutes
AHG addition delayed for 40 or more minutes AHG must be added immediately after washing to prevent the possibility of a false negative; a false negative can occur in this situation because previously bound globulins may dissociate from red cells, leaving insufficient antibody coating on the red cells to produce a reaction, or free antibody may directly neutralize antiglobulin reagent. Overcentrifugation, use of tubes containing silicone gel, and use of saline stored in glass or metal container can all result in false-positive results.
Which antibody identified in prenatal specimens is never a cause of hemolytic disease of the fetus and newborn? Anti-D Anti-c Anti-E Anti-I
Anti-I Anti-I is a common autoantibody that can be found in virtually all sera. It is benign (not associated with in vivo red blood cell destruction). It is usually a weak, naturally occurring, saline-reactive IgM agglutinin. Rh antibodies are primarily IgG and Rh antigens are well developed early in fetal life. While the D antigen is the most immunogenic, c antigen is the next most likely Rh antigen to elicit an immune response, followed by E, C, and e. Rh antibodies formed by the Rh negative pregnant women coat the fetal red blood cells that carry the corresponding antigens. The coated fetal cells are removed from the fetal circulation (hemolytic disease of the fetus and newborn).
What is considered the most clinically significant antibody outside of the Rh system?
Anti-K
Of the following blood group antibodies, which has been most frequently associated with severe cases of hemolytic disease of the fetus and newborn (HDFN)? Anti-A,B Anti-Le^a Anti-K Anti-M
Anti-K Of those listed, anti-K is most frequently associated with severe forms of HDFN. Anti-K is considered the most clinically significant antibody outside of the Rh system. Kell antigens are found on both immature and mature red blood cells leading to destruction of precursor and circulating red blood cells. Anti-A,B is frequently implicated in HDFN, but the disease is generally mild, often subclinical. Anti-Le^a is not implicated in HDFN for two reasons; the antibody is generally IgM and the Lewis system antigens are poorly developed at birth. Anti-M is not usually implicated in HDFN due to the fact that more anti-M is IgM.
In the ABO blood group system, the A antigen is inherited in what relation to the B antigen? Codominant Dominant Recessive Amorphic
Codominant In the ABO blood group system, the A and B antigens are inherited in a codominant fashion, meaning that a person who inherits the A antigen from one parent and the B antigen from the other will demonstrate both the A and B antigens. Both the A and B antigens are inherited in a dominant fashion over the O antigen. If a person inherits an A or B antigen from one parent and an O antigen from the other, the A or B antigen will be demonstrated. The O antigen is recessive to the A and B antigens. A person must inherit the O antigen in the homozygous form, OO, in order to demonstrate it phenotypically. The O antigen is amorphic, meaning that it does not produce any demonstrable antigen.
What is cold agglutinin disease?
Cold Agglutinin Disease (CAD) presents when red cells agglutinate at room temperature. In vivo, a cold autoantibody attaches to red cells in the colder extremities and activates the complement cascade. As the blood warms closer to the core of the body, the autoantibodies dissociate from the red cells, and more complement is activated. This is often associated with autoanti-I or autoanti-i.
For which of these reasons would a molecular method not be used? Determine blood type when the DAT is positive Complex Rh genotypes (weak D expression) Donor antibody screening Type fetal blood
Donor antibody screening Applications of molecular testing in blood bank include donor antigen screening not donor antibody screening. Other applications include determining blood type when the DAT is positive, identifying complex Rh genotypes, and typing fetal blood.
Persons with hemophilia A or hemophilia B that demonstrate inhibitors should be given which of the following products? Factor VIII concentrates Factor IX concentrates Factor VIIa Factor X
Factor VIIa Factor VIIa is used for persons with hemophilia A or hemophilia B that demonstrate inhibitors. Factor VIII is used for persons with hemophilia A with no inhibitors. Factor IX is used for persons with hemophilia B with no inhibitors. Factor X could be used for persons demonstrating Factor X deficiency.
A secondary immune response is generally associated with which of the following antibodies? IgG IgA IgM IgD
IgG The secondary or anamnestic response has a short lag phase, typically with higher titers than the primary immune response, and IgG predominates. IgA is the immunoglobulin class associated with mucosal immunity. IgM is the immunoglobulin class that predominates in a primary immune response. IgD is involved in the maturation process of B cells, which become immunoglobulin-secreting plasma cells.
The majority of Lewis antibodies are of which immunoglobulin class? IgM IgG IgA IgE
IgM Lewis antibodies are often naturally occurring and they occur without red blood cell stimulus. They are generally IgM and do not cross the placenta. Anti-Lea is the most commonly encountered of the Lewis antibodies.
Which of the following sources of error will give a false negative result in antihuman globulin testing? Low pH of saline Dirty glassware Samples collected in gel separator tubes Refrigerated specimen
Low pH of saline A low pH of saline is indicated as a false negative source of error in antihuman globulin testing. Dirty glassware, samples collected in gel separator tubes, and refrigerated specimens are all indicated as false-positive sources of error in antihuman globulin testing.
Which of the following is responsible for causing transfusion associated graft-versus-host disease? Platelets Granulocytes Monocytes Lymphocytes
Lymphocytes Transfusion associated graft-versus-host reactions are caused by the engrafting of immunocompetent T lymphocytes into a severely immunosuppressed recipient. They can be prevented by gamma irradiation of cellular blood components. Platelets, monocytes, and granulocytes are not involved in transfusion associated graft-versus-host disease.
Which of the following situations warrants postpartum administration of Rh immune globulin (RhIg)? Mother: D positive; Cord: D negative Mother: D negative; Cord: D negative Mother: D negative; Cord: D positive Mother: D positive; Cord: D positive
Mother: D negative; Cord: D positive A non-immunized D negative woman who delivers a D positive infant should receive a full dose of RhIg within 72 hours of delivery. RhIg prevents alloimmunization in D negative mothers exposed to D positive cells. Therefore, it is not needed if the mother is D positive or when the mother and baby are both D negative.
Which specific immunodominant sugar is responsible for A (blood group A) antigenic specificity? L-fucose D-galactose N-acetyl-D-galactosamine Glucose
N-acetyl-D-galactosamine Once substance H is developed, the addition of the sugar N-acetyl-D-galactosamine to the terminal position of the chain gives the molecule "A" antigenic activity. L-fucose is the terminal sugar responsible for H (blood group O) specificity. D-galactose is the terminal sugar responsible for B (blood group B) specificity. Glucose is formed in the precursor structure but not as an immunodominant sugar that determines blood group specificity.
What can cause a false positive reaction while performing the DAT technique?
Overcentrifugation, use of tubes containing silicone gel, and use of saline stored in glass or metal container can all result in false-positive results.
A specimen from a 23-year-old female patient who is a Bombay phenotype arrives in the blood bank. You observe the following reactions upon tube testing. Which of the following statements is true? Type AB red blood cells can be transfused to this patient Type O red blood cells can be transfused to this patient in an emergency Type O NEG blood can be transfused to this patient Patient can receive only Bombay phenotype blood
Patient can receive only Bombay phenotype blood Individuals with the Bombay phenotype react as group O in forward and back type testing. However, individuals with the Bombay phenotype produce anti-H in addition to anti-A and anti-B expected in group O individuals. H substance (L-fucose) is present on the red cells of 99.99 percent of the population and is expressed to the greatest extent on the red cells of type O individuals. Therefore, it would be very dangerous to transfuse this patient with any red cells that express the H antigen. Such an individual can only receive blood from a donor of the Bombay phenotype.
What is the deferral period from donating blood for someone who is or has taken Tegison© for severe psoriasis? Permanent deferral 1 month following last dose 2 weeks No deferral
Permanent deferral Persons taking or who have ever taken Tegison© are permanently deferred. Blood or blood products from persons who have ever taken Tegison© can cause birth defects if transfused to a pregnant woman. Other medications such as Proscar© and Avodart © (both used to treat enlarged prostates), Propecia© (used to treat bladness), Accutane© (used to treat severe acne), and Soriatane© (used to treat severe psoriasis) are all cause for deferral. Proscar©, Propecia©, and Accutane© users are deferred for one month following the last dose. Persons who have used Avodart © are deferred for six months following the last dose. Persons who have used Soriatane© are deferred for three years following the last dose.
Who would be a candidate, at 28 weeks gestation and had a negative antibody screen, to be injected with Rh immune globulin (RhIg)? Rh positive mother with Rh negative fetus Rh positive mother with Rh positive fetus Rh negative mother with Rh negative fetus Rh negative mother with Rh positive fetus
Rh negative mother with Rh positive fetus Criteria for antepartum administration include D negative mothers when the fetus is either D positive or unknown. D positive mothers are not candidates for RhIg. A D negative mother whose infant is known to be D negative is not a candidate for RhIg. Also, mothers who have been previously immunized to D are not candidates for RhIg.
Anti-U antibodies can be produced by which of the following genotypes? M-N- S+s+ S+s- S-s-
S-s- Absence of or an altered glyocyphorin B can result in red cells lacking the S, s, and U antigens. These individuals, if exposed to blood with S antigens, s antigens, or both will also be exposed to the U antigen and have the potential to produce anti-U. In this same scenario, the person receiving blood could also produce anti-S and/or anti-s. The U antigen is present on red cells when a person has S antigens, s antigens, or both.
Which of the following is the MOST IMPORTANT first step to take when a patient is transfused with un-crossmatched RBCs that turn out to be incompatible? Order new blood specimens for the investigation. Identify the antibody. Perform an immediate spin crossmatch to rapidly determine incompatibility. Stop any transfusion in progress.
Stop any transfusion in progress. Stopping any transfusion in progress is the most important first step since severity of hemolytic transfusion reactions partly depends on the volume of red cells transfused. Ordering of a new blood specimen should occur after the transfusion is stopped. Identifying the antibody will be necessary in order to determine the severity of the incompatibility and to be able to crossmatch compatible units. Performing an immediate spin crossmatch will only detect IgM (ABO) antibodies and should be performed as part of the transfusion reaction workup, but only once the transfusion is stopped.
Wiener to Fisher-Race Conversions
Wiener ---> Fisher-Race R0 ---> Dce R1 ---> DCe R2 ---> DcE Rz ---> DCE r ---> ce r' ---> Ce r" ---> cE ry ---> CE
Which of the following is considered a high-incidence antigen? K (big K) C (big C) c (little c) k (little k)
k (little k) It occurs in approximately 98.8% of white donors and almost 100% of black donors K (big K) appears in approximately 9% of white donors and is rare in black donors. C (big C) appears in approximately 68% of white donors and 27% in black donors. c (little c) appears in approximately 80% of white donors and approximately 97% of black donors.
In the Kleihauer-Betke test, a maternal blood smear is treated with acid and then stained with counterstain. The fetal cells contain fetal hemoglobin, which is resistant to acid and will remain pink. Since the calculated volume of fetomaternal hemorrhage is an estimate, how many additional RhIg vials need to be added for the dose? 1 1.5 2 3
1 After 2000 cells are counted, the percentage of fetal cells is determined, and the volume of fetal hemorrhage is calculated by the formula: number of fetal cells X maternal blood volume / number of maternal cells = volume of fetomaternal hemorrhage. Because the Kleihauer-Betke is an estimate, one vial is added to the calculated answer.
A unit of red blood cells that was collected on 15 June 2009 and frozen with glycerol at -80° C on 20 June 2009 will expire on what date? 14 June 2010 15 June 2010 20 June 2019 15 June 2019
15 June 2019 The correct answer is June 15, 2019; 10 years from collecting date. Blood is sometimes frozen to maintain an inventory of rare units or extend the expiration date of autologous units. Currently, the FDA licenses frozen RBCs for a period of 10 years following collection date. Glycerol is the most commonly used agent and is added to RBCs within 6 days of collection. The recommended interval between removing the RBC unit from refrigeration and placing the glycerolized cells in the freezer should not exceed 4 hours. So, based on this information, the correct answer should be 10 years from the date of collection, which in our case is June 15, 2019; 10 years from collection date. When the blood is needed, it is thawed and deglycerolized and the expiration date is changed to 24 hours from the time of thawing.
In which of the following sections of CFR Title 21, Good manufacturing practices, would you find requirements for quality control testing of donor units of platelets? 21 CFR 211.22 Responsibilities of a Quality Control Unit 21 CFR 211.80 Control of Components, Drug Product Containers and Closures 21 CFR 606.140 Laboratory Controls 21 CFR 640.25 Platelets - General Requirements
21 CFR 640.25 Platelets - General Requirements The correct answer is 21 CFR 640.25. This section contains the requirement to test a minimum of 4 units per month. The pH must be at least 6.2 at the end of the dating period. The plasma volume and the platelet count must also be measured. The minimum platelet count in a whole blood derived Platelet is 5.5 x 1010 in 75% of the units tested. There are no quality control requirements for platelets in 21 CFR 211.22; 21 CFR 211.80; or 21 CFR 606.140.
What is the increase in the risk for developing antibodies against red cell antigens (RBC alloimmunization) for patients who are characterized as chronically transfused patients? 1% - 4% 2% - 8% 5% - 10% 30% or greater
30% or greater In chronically transfused patients, such as those with thalassemia, autoimmune hemolytic anemia, and sickle cell disease, the risk of developing antibodies against red cell antigens (RBC alloimmunization) increases by 30% or more.
Red cells units containing CPDA-1 as an anticoagulant-preservative may be stored for how long prior to transfusion? 5 days 15 days 25 days 35 days
35 days Red cell units containing CPDA-1 may be stored at 1-6oC for up to 35 days. None of the other choices are associated with storage limits according to current regulations. Red cell units containing CPD or CP2D may be stored for 21 days prior to transfusion. Additive solutions such as AS-1, AS-3, and AS-7 increase the storage limit of red cell units to 42 days.
When preparing platelet concentrates from whole blood, after the second spin and excess plasma has been expressed from the platelets, what is the next step in platelet preparation? Allow the platelets to rest for 1-2 hours at 20-24°C. Agitate the platelets vigorously for 1-2 hours at 20-24°C. Pool several platelet concentrates together immediately and irradiate. Freeze the platelet concentrate immediately at < 18°C.
Allow the platelets to rest for 1-2 hours at 20-24°C. After the second spin in the preparation of platelets, the excess plasma is expressed, leaving approximately 50-70 mL of plasma on the packed platelet concentrate. The platelet bag should be allowed to rest at 20-24°C for 1 - 2 hours. After resting, the platelet component can be gently massaged if needed to resuspend the platelets, and the bag is placed on a rotator for gentle agitation. Platelet concentrates should never be vigorously agitated. Platelet concentrates have to be processed as above, and all testing completed before they can be pooled together for transfusion and may/may not need to be irradiated depending upon the recipient's needs. Platelet concentrates are not frozen.
Based on the following results obtained against a patient's red cells, what will the genotype look like in this example? Anti-C = 4+ Anti-c = 4+ Anti-E = 0 Anti-e = 4+ Anti-D = 0
Based on the positive antigen results given, the most likely Fisher-Race phenotype is Ce/ce. The patient lacks D antigen and presents with c, e, and C antigens. It is necessary to convert between Wiener shorthand designation and Fisher-Race nomenclature to make this determination. For this case, the patient's Fisher-Race phenotype (Ce/ce) translates into r'r (Ce/ce). Alternatively, the lack of D antigen can be denoted as a lowercase 'd' in the Fisher-Race phenotype (i.e. dCe/dce). R0R0 converts into Dce/Dce indicating a presence of D antigen and a lack of C antigen. rr converts into dce/dce and does not indicate the presence of C antigen. R1R2 converts into DCe/DcE indicating the presence of both D and E antigens. Wiener/Fisher-Race R0/Dce R1/DCe R2/DcE Rz/DCE r/ce r'/Ce r"/cE ry/CE
The MOST reliable method for determining the appropriate dosage of Rh immune globulin to give to an identified Rh immune globulin candidate after delivery is: Kleihauer-Betke method Flow cytometry Rosette test Panel cells
Flow cytometry Flow cytometry is the most reliable method of those listed as it is an automated quantitative method. The Kleihauer-Betke test is quantitative, but the test cannot be performed quickly and is subjective. The rosette test is qualitative and cannot be used to determine the number of vials that must be administered. The panel cells can only be used to identify the presence of the antibody.
Which type of blood component is most implicated in bacterial contamination? Platelets Packed red cells Fresh frozen plasma Cryoprecipitate
Platelets Platelets are the most common product implicated in bacterial contamination cases. This is because the room temperature storage requirement provides an adequate environment for bacterial growth. Contamination rates in the United States has been estimated to be 0.2% for red blood cells and as high as 10% for platelets. Since fresh frozen plasma and cryoprecipitate involve freezing of the components, bacteria will not survive.
All of the following are benefits of autologous donation EXCEPT: Reduces exposure to infectious diseases Readily available in case of an unexpected emergency Reduces demand for homologous blood transfusions Eliminates sensitization to cellular blood components
Readily available in case of an unexpected emergency Autologous (one donates to self) units must be drawn before they are needed and must be readily available at the time of procedure. As a result of the collection process, autologous units are generally not available for use in emergencies. Advantages to using autologous blood includes all of the following: reduces exposure to infectious diseases that may be present in homologous or allogeneic blood products, lower demand on homologous blood products that may be used for other patients, and eliminates sensitization to cellular blood components which lowers the risk of transfusion reactions.
As a student in a blood bank laboratory, you are tasked with determining the identification of an antibody as part of your practical exam. You are asked to use an enzyme treated red cell panel during the process of antibody identification. Which of the following antibodies is enhanced by enzyme treatment of red cells? MN and Duffy antibodies Rh, Lewis, and Kidd antibodies Rh, A, B, and S antibodies Duffy, A, and B antibodies
Rh, Lewis, and Kidd antibodies Rh, Lewis, Kidd antibodies: Antibodies from these blood group systems will be enhanced (react more strongly) when tested against enzyme-treated reagent red blood cells. While antibodies in the Rh, Lewis, Kidd, and ABO blood group systems are enhanced when tested against red blood cells that have been enzyme-treated, antigens in the MNS and Duffy blood group systems are degraded when treated with enzymes, so antibodies against these antigens will be weaker or non-reactive when tested against enzyme-treated red blood cells. Therefore, the first choice is incorrect because it includes MN and Duffy antibodies; The third choice is incorrect because it includes S antibodies; The last choice is incorrect because it includes Duffy antibodies.
In the evaluation of a positive DAT result, all of the below techniques can be used to dissociate the antibody(ies) form the RBCs EXCEPT: EDTA-glycine Saline replacement Chloroquine diphosphate Murine monoclonal antibodies
Saline replacement If IgG antibodies or complement are coating the RBC surface, then a positive DAT result is reported. The next step in the testing process is to dissociate (or remove) the antibodies from the RBC surface. An elution technique is performed to release, concentrate, and purify antibodies. Chloroquine diphosphate, EDTA-glycine, and murine monoclonal antibodies may be used for the purpose of removing IgG antibodies from the RBC surface. The antibodies are freed into a solution known as an eluate. The eluate may be used for the identification of the antibody(ies). In the saline replacement technique, saline is used to free RBCs clumped in rouleaux (coin-like stacking of RBCs) formation. If it is pseudo-agglutination, then the RBC clumps will disperse after the addition of saline. If true agglutination is present, then the RBCs will remain clumped together after the addition of saline.
When is testing for weak D optional (not required)? Testing for weak D on potential transfusion recipient samples. Testing on donor red blood cells. Testing cord blood on infants born to Rh-negative moms Testing for Rh immune globulin workups.
Testing for weak D on potential transfusion recipient samples. Testing for weak D on potential transfusion recipient samples is not required. However, some facilities will test for weak D on recipient samples. If the initial testing (immediate spin) is the only testing performed on the weak D individual, they would be considered Rh-negative and would receive Rh-negative blood. Since recipients who are weak D positive are considered Rh-positive, they can receive either Rh-positive or Rh-negative blood. The AABB Standards require testing for weak D on donor cells that do not directly agglutinate with anti-D reagents. Weak D testing is also performed cord blood from infants born to Rh-negative moms and on Rh immune globulin workups.
Kernicterus can cause brain damage in newborns suffering from severe HDFN. This is due to a buildup of which of the following substances? Unconjugated bilirubin Iron Haptoglobin Conjugated bilirubin
Unconjugated bilirubin Hemolytic disease of the fetus and newborn leads to the destruction of fetal red blood cells caused by a maternal antibody (IgG) that can cross the placenta. During pregnancy, the unconjugated or indirect bilirubin released from the red cell destruction can cross the placental where it is conjugated by the maternal liver and excreted by the mother. After birth, the buildup of bilirubin becomes a significant problem for the baby because the baby's liver is unable to conjugate the indirect bilirubin efficiently (and the maternal liver is no longer there), and therefore the bilirubin is not excreted. The unconjugated bilirubin can reach toxic levels (usually greater than 18-20 mg/dL) and cause damage to the infant's brain. If this is not treated, permanent damage can occur. This is dangerously termed kernicterus. Kernicterus is not due to an increase in iron, haptoglobin, or conjugated bilirubin. Additional information: Haptoglobin is decreased in hemolytic conditions, including hemolytic disease of the fetus and newborn. It (haptoglobin) binds to free hemoglobin dimers circulating in peripheral blood.
The addition of Low Ionic Strength Solution (LISS) to the testing environment when performing an indirect antiglobulin test is designed to do what? Lowering the zeta potential Increasing the zeta potential Bind IgG antibodies attached to patient RBC's Bind IgM antibodies found in patient serum or plasma
Lowering the zeta potential LISS lowers the zeta potential. The addition of LISS does not increase the zeta potential. LISS does not bind IgG antibodies attached to patient RBC's. That is accomplished by the addition of antihuman globulin. LISS does not bind IgM antibodies found in the patient serum or plasma. Because IgM is a pentamer, lattice formation naturally occurs when it binds in a solution with antigens to which it has specificity.
Antibody identification interpretations would be considered correct 95% of the time or have a P value of 0.05 (5% probability that the result is due to chance) if you have: 2 positive reactions to rule in an antibody and 2 negative reactions to rule out an antibody 1 positive reaction to rule in an antibody and 3 negative reactions to rule out an antibody 3 positive reactions to rule in an antibody and 3 negative reactions to rule out an antibody 3 positive reactions to rule in an antibody and 1 negative reaction to rule out an antibody
3 positive reactions to rule in an antibody and 3 negative reactions to rule out an antibody A P value is used to statistically determine the probability that a certain set of events or results will happen by random chance. A P value of 0.05 means that there is a 5% chance that the pattern of reactivity is due to something other than the suspected antibody. This can also be interpreted as the data will be correct 95% of the time. Using 3 cells to rule in and 3 cells to rule out gives the highest probability of the above listed answers (P value of 0.05). By comparing the patterns of reactivity and non-reactivity, we can more safely assume that an observed pattern is not the result of chance alone.
The following statements are true regarding the Lewis blood group EXCEPT: Antigen expression is influenced by secretor status Antigens are adsorbed onto the red cells from the plasma Antigens are a structural component of the red cell membrane ABO group affects antigen expression
Antigens are a structural component of the red cell membrane Lewis antigens are not a component of the red cell membrane and, in fact, are not produced by the red cell at all. They are passively adsorbed onto the red cell membrane from the plasma. Expression of Lewis antigens is influence by secretor status. Secretors who have at least one copy of a Le gene express Le^b on their red cells while nonsecretors with a Lewis gene express Le^a on their red cells. Lewis antigens are unique as they are not intrinsic to red cells but instead passively adsorbed onto the red cells from the plasma. ABO grouping does affect antigen expression since the addition of an immunodominant sugar to 1H chain can result in the formation of ALe^b and BLe^b (in individuals who carry at least one Se gene and Le gene).
The "recognition unit" of the classical complement pathway refers to which of the following? C5b, C6, C7, C8, C9 C1q C3a C4
C1q C1q is referred to as the "recognition unit" in the classical complement pathway. C5b, C6, C7, C8, and C9 make up the membrane attack complex. C3a works as a natural substrate on C4b2a. C4, along with C2, are part of the classical complement pathway.
Which of the following may result in a false negative reaction when performing Rh typing? Rouleaux Centrifuging too long Cold agglutinins Failure to follow manufacturer's directions precisely
Failure to follow manufacturer's directions precisely The reagents must be used according to the manufacturer's instructions for use. Failure to follow the instructions can lead to false negative results. Directions should be reviewed and repeated if needed. Rouleaux, centrifuging too long, and cold agglutinins all lead to false positive results in Rh typing.
A2B is suspected when a patient's ABO typing has the following results: Patient's red cells forward types as AB with anti-A1 present in the patient's serum. Patient's red cells forward types as A with anti-A1 and anti-B present in the patient's serum. Patient's red cells do not react with either Anti-A nor Anti-B, and anti-A1 and anti-B are present in the patient's serum. Patient's red cells forward types as A with a mixed field reaction of the patient's red cells with Anti-A, and anti-B detected in the patient's serum.
Patient's red cells forward types as AB with anti-A1 present in the patient's serum. A2B individuals may produce anti-A1. 22-35% of A2B individuals have anti-A1 in their serum. A2B individuals forward type as AB, and may demonstrate anti-A1 in their serum. A2 individuals forward types as A, and may demonstrate anti-A1 in their serum. A2 individuals will have anti-B in their serum. 1-8% of A2 individuals have naturally occurring anti-A1 in their serum. A patient whose red cells do not react with either Anti-A nor Anti-B, and have anti-A1 and anti-B are present in the their serum is type O. The A3 subgroup RBCs will have a mixed field pattern of agglutination with anti-A reagents.
In the Coombs phase of a crossmatch, what is the proper procedure to follow if the Check Cells give a negative reaction? Repeat procedure with new AHG reagent and check the cell washer. Add additional Check Cells and dilute with 100% distilled water. Add additional AHG reagent plus proteolytic enzymes to enhance the reaction. Accept the crossmatch results as correct - nothing further needs to be done.
Repeat procedure with new AHG reagent and check the cell washer. The Check Cells are added when a negative result is obtained at the Combs phase of testing to ensure that the AHG reagent was added and was not neutralized. The addition of Check Cells following a negative result at the Combs phase should yield a positive result. If the Check Cells are negative, then the procedure must be repeated with a new AHG reagent to ensure that the reagent is working properly. It is also recommended to check the cell washer to ensure that the cell buttons are not being under- or over-washed. Adding additional Check Cells diluted with 100% distilled water would hemolyze the cells in the tube. Proteolytic enzymes are used as an enhancement reagent to the reagent red blood cells for antibody detection and identification; they are not used in compatibility testing. A negative result at the Combs phase of compatibility testing is an invalid result and must be resolved before transfusing the patient.
How are antibodies to the ABO blood group antigens unique? Laboratory tests are available for their identification. The antibodies are naturally occurring to antigens that are absent from the red cell membrane. The antibodies are formed after the individual has been immunized. The antibodies are IgM
The antibodies are naturally occurring to antigens that are absent from the red cell membrane. The ABO blood group is the only blood group in which antibodies naturally appear to the antigens absent on the red cell membrane. Antibodies to other blood group systems are acquired after contact with the corresponding antigen. Laboratory tests are available and routinely performed to identify antibodies to ABO antigens and most other clinically significant antibodies (ex. Rh, Kidd, Kell, Duffy, and others). Individuals do not need to be immunized for ABO antibody production to start. Antibody production is naturally occurring, with production starting at birth. Most ABO antibodies are of the IgM class, but this is not unique to the ABO blood group. For example, anti-M and anti-N are usually IgM.
Which of the following transfusion reactions can a diagnosis be more firmly established by evaluating B-type natriuretic peptide (BNP) levels before and after transfusion? Transfusion Associated Circulatory Overload (TACO) Delayed Hemolytic Transfusion Reactions Transfusion Associated Sepsis Allergic Transfusion Reactions
Transfusion Associated Circulatory Overload (TACO) Transfusion Associated Circulatory Overload (TACO) is difficult to distinguish from Transfusion Related Acute Lung Injury (TRALI). A post-transfusion to pretransfusion BNP ratio of 1.5 points is diagnostic of TACO. Delayed Hemolytic Transfusion Reactions testing includes the DAT, free plasma hemoglobin, hemoglobin, LDH, total and direct bilirubin, haptoglobin, free urine hemoglobin, and hemosiderin in urine. Transfusion Associated Sepsis testing includes blood cultures on the recipient and a gram stain and culture on the transfused component. Allergic transfusion reactions are diagnosed based on anaphylactic symptoms of the patient during transfusion of the component.
Which of the following noninfectious complications of blood transfusion is prevented by the irradiation of blood components? Anaphylactic reactions Febrile non-hemolytic reactions Transfusion-related acute lung injury (TRALI) Transfusion-associated graft versus host disease (TA-GVHD)
Transfusion-associated graft versus host disease (TA-GVHD) Irradiation prevents the proliferation of donor T lymphocytes in blood components. T lymphocytes in blood components may cause TA-GVHD in patients who are immunocompromised, who are receiving components from a blood relative, or who receive HLA-matched components. Washed components or components from IgA-deficient donors are indicated for patients at risk for anaphylactic reactions. The incidence of febrile non-hemolytic reactions has been reduced through the implementation of universal leukoreduction. One mitigation strategy to reduce the incidence of TRALI is to collect components from male donors, female donors who have never been pregnant, or female donors who have been tested since their last pregnancy and are negative for HLA antibodies.
Which organism is MOST likely responsible for septic reactions associated with red blood cell transfusions? Yersinia enterocolitica Escherichia coli Enterobacter species Streptococcus species
Yersinia enterocolitica The transfusion of small amounts of bacterially contaminated blood can be fatal or cause serious morbidity. Any contaminating bacteria in the donor unit that are unable to survive at 4oC die after several days of storage. Yersinia enterocolitica can thrive at 4oC and it can promote transfusion reactions.
