blood group immunology
Which of the following cells are capable of producing antibodies? Please select the single best answer Thrombocytes Macrophages Lymphocytes Neutrophils
B lymphocytes are responsible for humoral immunity. B lymphocytes are activated and differentiate into a plasma cell. Antibodies are then made towards the antigen, initiating this response. Thrombocytes are integral in primary hemostasis, while macrophages and neutrophils phagocytize and degrade foreign pathogens.
The "recognition unit" of the classical complement pathway refers to which of the following? The correct answer is highlighted below C5b, C6, C7, C8, C9 C1q C3a C4
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.
The immediate spin phase of an indirect antiglobulin test (antibody screen and antibody identification) could most likely lead to the detection of which of the following? Please select the single best answer Clinically significant warm antibodies Clinically significant cold antibodies Clinically insignificant warm antibodies Clinically insignificant cold antibodies
Clinically insignificant cold antibodies Feedback The immediate spin phase may lead to the detection of clinically insignificant cold antibodies. Clinically significant warm antibodies can be detected after 37 °C incubation and/or the addition of antihuman globulin.
Which specific immunodominant sugar is responsible for A (blood group A) antigenic specificity? The correct answer is highlighted below L-fucose D-galactose N-acetyl-D-galactosamine Glucose
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.
Rh antibodies generally: The correct answer is highlighted below React best at 4°C. React best at room temperature. Generally do not react at any temperature. React best at 37°C.
React best at 37°C. Feedback The correct answer is react best at 37°C. Rh antibodies react best at 37°C, they do not react at 4°C or room temperature.
Which of the following immunoglobulins are capable of fixing complement by the classical pathway? The correct answer is highlighted below IgG and IgA IgM and IgA IgG and IgM IgG and IgD
The correct answer is IgG and IgM. IgG and IgM can fix complement via the classical pathway. IgA can fix complement via the alternative pathway. IgD is not able to fix complement.
Most antibodies present in cord blood are of ________ origin. The correct answer is highlighted below Fetal Maternal Paternal Maternal and paternal
maternal Infants who are less than 6 months old usually do not produce alloantibodies. Newborns may have passive antibodies of maternal origin that crossed the placental, but they do not have passive antibodies of paternal origin.
From the IgG molecule illustration, which region is the heavy chain? The correct answer is highlighted below A B C D
A = Heavy chain B = Light chain C = Antigen binding site D = Variable region
ABO antibodies are classified as which of the following two immunoglobulin classes? The correct answer is highlighted below IgG and IgM IgM and IgA IgA and IgG IgE and IgM
ABO antibodies include the IgM and IgG immunoglobulin classes. IgA and IgE are important immunoglobulin class (playing roles in mucosal immunity and allergic reactions respectively) but are not generally ABO antibodies.
Which antibody is present in the blood of an individual with the Bombay phenotype that will cause agglutination with any non-Bombay individual's blood? The correct answer is highlighted below Anti-AB Anti-B Anti-A Anti-H
Anti-H is produced by individuals with the Bombay phenotype because they are deficient in the H antigen. Since the H antigen is the building block for A and B antigens, they will also lack expression of the A and B antigens. Due to the presence of anti-H in the serum of a person with the Bombay phenotype, only blood from another person with the Bombay phenotype may be transfused because there are H antigens on all the other blood groups.
What is the explanation for a discrepancy in the following front type and back type in a newborn? Anti-A = neg Anti-B = neg A1 cells = neg B cells = neg Red cells are totally coated with antibody. The newborn is missing antigens. The baby's antibodies are undeveloped. Unable to determine.
At birth, ABO antibodies are generally absent or of maternal origin. ABO antibody production begins at about 4 - 6 months of age.
When administering fresh frozen plasma (FFP), which one of the following is considered standard blood bank practice? The correct answer is highlighted below 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
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 packed RBCs could be transfused to a group O patient? The correct answer is highlighted below Group A Group B Group AB Group O
Group O Feedback Transfusion of red cells of any ABO type other than O to a group O patient is likely to cause a hemolytic transfusion reaction. Group O individuals naturally have anti-A, anti-B, and anti-A,B. These antibodies would bind and cause hemolysis of all red blood cells that are not group O (ex. group A, group B, and group AB).
Which class of immunoglobulins is implicated in hemolytic disease of the fetus and newborn (HDFN)? The correct answer is highlighted below IgA IgM IgE IgG
IgG Feedback IgG antibodies are implicated in HDFN. They are small enough to cross the placental barrier to enter fetal circulation. IgA antibodies are primarily found in secretions and mucosal tissue in a dimer form (2 antibodies joined together by a J chain). IgM is a large pentamer (5 antibody molecules joined together by J chains) and cannot cross the placenta. IgE antibodies are found in trace concentrations in serum and are implicated in histamine release from Basophils in an allergic reaction.
What characteristic is usually associated with IgM antibodies directed against red cells? The correct answer is highlighted below React best at 37oC Appear after heated incubation Are identified using the AHG test React best at room temperature
IgM antibodies typically react best at room temperature. The other choices listed including: reacting best at 37oC, appearing after heated incubation, and identification using the AHG test, are all characteristics of most IgG immunoglobulins, but not IgM immunoglobulins.
A primary immune response is generally associated with which antibody? The correct answer is highlighted below IgG IgA IgM IgD
IgM is a pentamer which is the predominant antibody produced during the primary immune response. Secondary antibodies are usually IgG.
Which Rh antibody might be produced if a unit of blood with Rh genotype DCe/dce is given to a patient with Rh genotype DCe/DCe? The correct answer is highlighted below Anti-C Anti-c Anti-D Anti-Cw
In this case, the c antigen is not present on the cells of the recipient. If this recipient is transfused with c-positive RBC units (i.e. DCe/dce), then there is a possibility that the recipient may form an antibody against the c antigen (anti-c) located on the donor RBCs. Exposure to the donor's RBC units (DCe/DCe) will not stimulate an immune response to D, C, or e antigens due to the expression of these antigens on the recipient's own RBCs.
Which of the following is the predominant immunoglobulin class for anti-A and anti-B antibodies in group B and group A individuals? The correct answer is highlighted below IgM IgG IgA IgE
Individuals normally produce antibodies directed against the A and/or B antigen(s) absent from their red blood cells (RBCs). These antibodies have been described as naturally occurring because they are produced without exposure to RBCs. The ABO antibodies are predominantly IgM, and they activate complement and react at room temperature or colder.
The majority of Lewis antibodies are of which immunoglobulin class? The correct answer is highlighted below IgM IgG IgA IgE
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.
What is the minimum volume (milliliters) of Rh positive red blood cells that would be needed to produce anti-D in an Rh negative individual? Please select the single best answer < 0.1 mL1 mL5 mL> 10 mLWhat is the minimum volume (milliliters) of Rh positive red blood cells that would be needed to produce anti-D in an Rh negative individual? Please select the single best answer < 0.1 mL 1 mL 5 mL > 10 mL
Rh antigens are highly immunogenic; the D antigen is the most potent. Exposure to less than 0.1 mL of Rh positive red blood cells can stimulate antibody production in a Rh negative person.
What kind of immunoglobulins are predominantly found in Rh immune globulin? The correct answer is highlighted below IgM anti-D IgG anti-D IgM anti-A,B IgG anti-A,B
Rh immune globulin is a solution of concentrated anti-D. It is prepared from pooled human plasma of patients who have been hyperimmunized and contains predominantly IgG anti-D. Because RhIg contains IgG anti-D, it can cross the placenta and sensitize fetal Rh positive red cells. Affected infants may be born with a weakly positive DAT, but significant hemolysis does not occur.
Which of the following antibodies is detected primarily in the antiglobulin phase of the crossmatch? The correct answer is highlighted below Anti-Fya Anti-M Anti-B Anti-P1
The Duffy system consists of Fya and Fyb. Antibodies to these antigens are IgG and are detected in the antiglobulin phase. Anti-M, Anti-B, and Anti-P1 are typically IgM antibodies and may agglutinate saline suspended cells at room temperature.
Which subset of effector lymphocytes is predominantly responsible for regulation of antibody production? The correct answer is highlighted below TH1 TH2 TH17 CD8+
The TH2 subset of CD4+ effector T lymphocytes (Helper T type 2) plays a significant role in the regulation of antibody production. This subset secretes IL-4, IL-5 and IL-13. IL-4 and IL-13 act on B cells to stimulate production of antibodies that bind to mast cells, such as IgE. TH2< cells mediate host defense against extracellular parasites, including helminths. They are important in the induction and persistence of asthma and other allergic inflammatory disorders. TH2 cells produce Il-4, Il-5, IL-9, IL-10, IL-13, IL-25 and amphiregulin, a protein member of the epidermal growth factor (EGF) family. The TH1subset of CD4+ effector T lymphocytes secrete interferon (IFN-?) that acts on macrophages to increase phagocytosis and killing of microbes, and on B lymphocytes to stimulate production of IgG antibodies that opsonize microbes for phagocytosis. But help for antibody production may be provided, not by classical TH1 cells most of which migrate out of lymphoid organs to sites of infection and inflammation, but by follicular helper T cells that remain in lymphoid organs and produce(IFN-?).The role of IFN-? has been established in mice but not in human beings. The TH17subset of CD4+ effector T lymphocytes mediate immune responses against extracellular bacteria and fungi. These cells are also responsible for, or participate in, the induction of many organ-specific autoimmune disorders. TH17 cells produce IL-17a, IL-17f, IL-21 and IL-22. Both IL-17a and IL-17f recruit and activate neutrophils during an immune response against extracellular bacteria and fungi. The CD8+ subset of effector T lymphocytes (Cytotoxic, Tc) are effector cells found in the peripheral blood that are capable of directly destroying virally infected target cells. After clearance of the virus, most effector CD8+ T cells contract due to apoptosis, but a small number of these CD8+ cells form a memory T-cell pool.
A delayed hemolytic transfusion reaction is most likely to be the result of which of the following antibodies? The correct answer is highlighted below Lea A Jka B
The correct answer is Jka. Jka antibodies are known to disappear from circulation quickly (often within a few weeks), which can cause a false-negative antibody screen and subsequent transfusion of antigen-positive units that will stimulate the patient to produce antibodies and can cause a delayed hemolytic transfusion reaction. A antibodies (all ABO antibodies) would cause an immediate hemolytic transfusion reaction. Lea antibodies are rarely implicated in acute hemolytic transfusion reactions but are NOT known to cause delayed hemolytic transfusion reactions. B antibodies (all ABO antibodies) would cause an immediate hemolytic transfusion reaction.
The primary antibody response takes an average of how many days? The correct answer is highlighted below 1-3 days 3-4 days 5-10 days 14-21 days
The primary immune response takes approximately one week, or 5-10 days, to occur. The secondary immune response typically has a shorter lag period, which is approximately 1-3 days. The primary immune response typically does not begin as early as 3-4 days. A lag time of 14-21 days is exceptionally long and would lead to additional issues with the infection.
Which characteristic best describes IgG antibodies produced against red blood cells? The correct answer is highlighted below Are naturally occurring Cannot be identified using the AHG test React best at room temperature React best at 37o Celsius
There are two types of antibodies that concern blood banking: one is naturally occurring and the other is immune. Most immune red blood cell antibodies are IgG antibodies that react best at 37oC and require the use of antihuman globulin for detection. Most naturally occurring antibodies are IgM cold agglutinins which react best at room temperature or lower.
Following the treatment of an IgG molecule with papain, which of the following will remain? The correct answer is highlighted below Two Fab fragments each with a light chain and a partial heavy chain attached with a disulfide bond Four separate light chains and two separate heavy chains One unit that consist of a two partial heavy chains, two light chains all attached with a disulfide bond Eight units, two complete light chains, and two heavy chains split in half
Two Fab fragments each with a light chain and a partial heavy chain attached with a disulfide bond Digestion with papain will cut above the disulfide bond that holds the heavy chains together, leaving two units, each with a partial heavy chain and a light chain held together with a disulfide bond. Digestion with urea and mercaptoethanol will remove all disulfide bonds leaving free units of light and heavy chains. Digestion with pepsin will cut below the disulfide bond, leaving one unit of two partial heavy chains and two light chains all attached with a disulfide bond. There is no digestive enzyme that results in eight units.
If Jka is showing dosage, how might reactions on an antibody panel appear? The correct answer is highlighted below Weaker if homozygous for Jka Stronger if heterozygous for Jka and Jkb Weaker if heterozygous for Jka and Jkb Both heterozygous and homozygous reactions would always be of equal strength
Weaker if heterozygous for Jka and Jkb The strength of reaction can be due to the number of antigens present on the red cells that can bind with the antibody present. Inheritance of antigens can be in the homozygous or heterozygous state. If the antigen is in the homozygous state, there is a double dose of the antigen present on the red cell. For antibody reactions showing dosage, antigen-antibody reactions will be stronger if in the homozygous state since there is more antigen to bind with the antibody. The antigen-antibody reactions will be weaker if in the heterozygous state since there is less antigen to bind with the antibody.
What section of an immunoglobulin molecule is responsible for the differences between immunoglobulin classes? Please select the single best answer Fc Fab Heavy chains Light chains
Antibodies are differentiated based on their heavy chains; different heavy chains create different isotypes. Humans have five different isotypes of immunoglobulins. The portion of antibodies where the C terminal region of each glycoprotein chain is located, is called the Fc portion. FC stands for fragment crystallizable. The FC portion of the immunoglobulin molecule after enzyme, papain, cleavage has structural identity and can be crystallized. The Fc portion has a constant amino acid sequence that defines the class and subclass of each antibody. The Fc portion is responsible for the biological activity of the antibody. Depending on the class of antibody, some of the functional activities of the Fc portion of antibodies include activating the complement pathway and binding to natural killer cells. Fab stands for fragment antigen binding and indicates the fragment after enzyme, papain, cleavage. The Fab section of an immunoglobulin molecule is the antigen-specific region. It has two light chains and portions of two heavy chains. It is a variable region that has two antigen-combining sites at the N-terminal ends. Light chains are small chains that are common to all immunoglobulin classes. L chains are of two subtypes: Kappa and lambda, which have different amino acid sequences and are antigenically different. Free light chains (FLCs)are incorporated into immunoglobulin molecules during B-lymphocyte development and expressed initially on the surface of immature B lymphocytes. In normal individuals, serum FLCs are rapidly cleared and metabolized by the kidneys depending on their molecular size.
The addition of Low Ionic Strength Solution (LISS) to the testing environment when performing an indirect antiglobulin test is designed to do what? The correct answer is highlighted below 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
The correct answer is that 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.
Which class of antibody can agglutinate erythrocytes (RBCs) after anti-human globulin (AHG) is added to the test tube? The correct answer is highlighted below IgA IgE IgG IgM
Some antibodies, such as IgG, do not directly agglutinate erythrocytes (RBCs). This incomplete or blocking type of antibody may be detected by an enhancement medium, such as anti-human globulin (AHG) reagent. If AHG is added, a second antibody binds to the antibody present on the erythrocytes. AHG is created to bind with IgG antibodies at the Fc portion of these antibodies. AHG will bind to both bound and unbound IgG antibodies. When IgG is bound to red blood cells, AHG produces visible agglutination in a test tube. IgA is the predominant immunoglobulin in secretions, such as tears and saliva. IgA forms a complex molecule termed secretory IgG, which is critical in protecting body surfaces against invading microorganisms because of its presence in seromucous secretions. IgE is unique in that it binds strongly to a receptor on mast cells and basophils. Together with antigen, IgE mediates the release of histamines and heparin from mast cells and basophils. IgM is a pentamer with multiple binding sites that enable higher avidity. IgM antibodies, such as anti-A and anti-B, readily agglutinate erythrocytes with the corresponding antigen, A or B, optimally at a colder temperature than IgG without any enhancement agent, such as anti-human globulin (AHG).
How are antibodies to the ABO blood group antigens unique? The correct answer is highlighted below 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 Feedback
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.
The immunoglobulin class responsible for the etiology of Hemolytic Disease of the Fetus and Newborn (HDFN) is: Please select the single best answer IgM IgG IgD IgE
The IgG class of immunoglobulins is the class associated with Hemolytic Disease of the Fetus and Newborn (HDFN). IgG is the smallest immunoglobulin class, MW 150,000. Antibodies to IgG subclasses, IgG1, IgG3, and IgG2 , are the immunoglobulins selectively transported from the maternal circulation to the fetal circulation through the placenta. Placental transfer is variable with the IgG2 subclass. In the third trimester, IgG is efficiently transported across the placenta from mother to fetus. It is now generally accepted that a cellular receptor, neonatal Fc receptor (FcRn), is pivotal for maternofetal IgG transport. Immune antibodies are formed in the mother due to antigenic stimulation. In hemolytic disease of the fetus and newborn (HDFN), maternal IgG antibodies can coat the erythrocytes of the fetus if fetal antigens specific to the maternal antibodies are present. This antigen-antibody reaction results in hemolysis primarily of erythrocytes. IgM has a molecular weight of 900,000. It is not associated with placental transfer from the mother to the fetus because of molecular size. IgD has a molecular weight of 180,000. It is not associated with placental transfer from the mother to the fetus because of molecular size. IgE has a molecular weight of 200,000. It is not associated with placental transfer from the mother to the fetus because of molecular size.
While ABO, Rh, Kell, Duffy, Kidd, SsU are clinically significant, which of the following antibodies generally react at only the Coombs phase (also known as Antihuman Globulin phase)? The correct answer is highlighted below Rh and Kell antibodies ABO antibodies Kell, Duffy and Kidd antibodies SsU and Kidd antibodies
The correct answer is: Kell, Duffy and Kidd antibodies. Kell, Duffy and Kidd antibodies are not only clinically significant, but they also react at only the Coombs phase. Rh antibodies can react at immediate spin and 37°C as well. ABO antibodies react at immediate spin and can react at 37°C as well. SsU antibodies can react at both immediate spin and at 37o phases as well.
The most significant blood group antibodies belong to which immunoglobulin classes? The correct answer is highlighted below IgA and IgD IgA and IgM IgE and IgD IgG and IgM
The most significant immunoglobulins in transfusion medicine are IgG and IgM. Most clinically important antibodies react at body temperature (37oC), are IgG, and can cause immune destruction of transfused red cells possessing the corresponding antigen. IgM antibodies react best at room temperature (20-22oC) or lower (to 4oC) and are usually not implicated in the destruction of transfused red cells. The important exception are the antibodies to ABO antigens. These antibodies are of the IgM class and react in vivo at room temperature and in vivo at body temperature. The transfusion of the wrong ABO blood group (antigen) would effectively activate the complement system and cause hemolysis of the transfused cells.
Why is it dangerous to transfuse a blood group O person with a unit of blood group A? The correct answer is highlighted below The patient will make antibodies to the type A blood. The group A blood may become the prominent blood group. The patient's Anti-O would destroy the donor's cells with severe consequences to the patient. The patient's anti-A would destroy the donor's cells with severe consequences to the patient.
The patient's anti-A would destroy the donor's cells with severe consequences to the patient. Feedback Group O individuals have naturally occurring anti-A, anti-B, and anti-A,B. These antibodies are "naturally occurring" because they are produced without being exposed to foreign red blood cells. Transfusing group A blood cells into a patient who is group O will result in a hemolytic transfusion reaction where the body would mount an immune response with anti-A against the foreign cells entering the body. The consequences of such a reaction can be very dangerous for the patient. The answer "The patient will make antibodies to the type A blood" is incorrect, because a person with blood type O already has anti-A and anti-B antibodies in his/her serum. Again, these are "naturally occurring" antibodies, the patient does not have to be exposed to type A, type B, or type AB blood to produce these antibodies. The group A red cells would be destroyed by the anti-A present in this group O patient so they would not change the patient's blood group. Lastly, there is no anti-O antibody. The O gene is an amorph, meaning is does not code for a transferase so there is no O antigen for an antibody to be made toward.
A primary immune response typically presents with which class of antibody? The correct answer is highlighted below IgG IgM IgA IgD
The primary immune response typically presents with the greatest level of IgM antibody. Detection of increased IgM antibodies typically demonstrates an acute or early exposure. The secondary immune response presents with a higher titer of IgG antibodies as compared to the primary response. The secondary immune response may also present with greater levels of IgA or IgE. IgD antibodies are typically not tested in the clinical setting.
Compared to the primary immune response, the secondary immune response typically demonstrates: The correct answer is highlighted below Less antibodies produced A longer lag time More antibodies produced A lower affinity
The secondary immune response typically presents with a greater number of antibodies that are produced as compared to the primary immune response. The primary immune response typically presents with the generation of less antibodies as compared to the secondary immune response. The secondary immune response presents with a shorter lag time as compared to the primary immune response. The secondary immune response typically presents with antibodies that have a higher affinity as compared to those from the primary immune response.
