Immunohematology Test 1 SG
Red cells coated with antibody
A group O person with warm autoimmune hemolytic anemia may demonstrate weak reactions in the forward grouping due to?
Clerical error
A patient was previously typed as blood group O. Forward grouping was negative with anti-A and anti-B. Reverse grouping showed reactivity with A1 cells and B cells. The blood bank tech reported this patient's type as A. what technical error occurred?
A higher dose of antigen is required to form antibodies
All of the following are characteristic of a secondary immune response except?
260,000
Approximately how many antigen sites can be found on A2 cells?
Reticuloendothelial system (liver and spleen)
Extravascular hemolysis occurs when red cells are coated with antibody; what organ sequesters these cells?
Repeat the antibody screen
An antibody screen is performed, and all three tubes are negative after adding the AHG reagent. Check cells are added, and the tubes are centrifuged. No agglutination occurs after the addition of check cells. What is the next course of action?
Antigen
An immunogenic substance that reacts with an antibody is?
Donation history
All of the following are important in evaluating a positive DAT except?
Lymphoma
All of the following conditions may produce a positive DAT except?
dosage
A person with the genotype MM shows a 3+ reaction when their RBCs are mixed with M antisera; whereas a person with the genotype MN shows a 1+ reaction when mixed with M antisera. What phenomenon is occurring here?
IgM, IgG
In an immune response, _____ antibodies are formed before _____.
Anti-IgG and anti-C3b-C3d
Polyspecific AHG contains?
Coombs
The antihuman globulin test was discovered in 1945 by whom?
O
The forward grouping of a patient showed no agglutination of patient cells with anti-A, nor anti-B, anti-sera. The reverse grouping showed agglutination with A1 and B cells. What is the person's blood group?
Heavy chain
The portion of the immunoglobulin molecule which determines class is?
O
The universal donor blood group, with regard to packed RBCs is?
O
What is the only possible phenotype of an offspring produced from two group O patients?
It detects red cells coated with antibody by bridging the gap between red cells
What is the purpose of the antihuman globulin (AHG) test in blood banking?
To remove all unbound protein
What is the purpose of washing cells in the AHG test?
Sensitization
When antigen and antibody combine, they are held together by noncovalent forces. With the absence of a visible lattice, this stage is called ___.
Increase serum-to-cell ratio
When there is an excess of antigen in a serologic test system, what course of action should be followed?
MN
Which blood group is the best example of codominantly inherited blood groups?
IgG
Which immunoglobulin class is found in the greatest concentration in serum?
IgG
Which of the following antibody classes are considered the most significant in blood banking because they react at body temperature?
Individuals have antibodies to antigens they lack without foreign stimulus
Which of the following is unique to the ABO system when compared with other blood group systems?
Inadequate washing
A patient came in for a routine type and screen prior to surgery. The antibody screen was negative at 37°C and AHG phase. Check cells did not produce agglutination. What is a possible explanation for this result?
IAT
A patient discovered to have anti-Fya in their serum. The medical lab tech needs to phenotype the patient cells for the corresponding antigen. What test is appropriate for phenotyping?
Acquired B
A patient who was recently diagnosed with an obstructed bowel became septic form proteus vulgaris. Prior to surgery, a routine type and screen was performed. Though this individual typed as an A two years ago, his forward type is consistent with an AB individual, albeit weaker in strength with anti-B. What is the reason for this discrepancy?
Saline dilution
A patient with multiple myeloma exhibits rouleaux formation in an immediate spin crossmatch. What procedure is recommended to distinguish true red cell agglutination from nonspecific agglutination?
AO
A woman with blood group A marries a man with blood group O. Their first child is blood group O. The mother's most probable genotype is?
Failure to warm reagents
All of the following are technical errors that could result in ABO discrepancies except?
AB, AA, and BB
An AB male mates with an AB female. What could be the genotype of the offspring?
Incubate patient serum and reagent cells for 15 minutes at room temperature
An elderly patient is documented as being type O. The forward grouping is negative with anti-A and anti-B. The reverse grouping showed no reactivity with A1 cells and B cells. What can be done to correct the discrepancy?
37 degrees C
At what temperature do IgG antibodies react optimally?
22 degrees C
At what temperature do IgM antibodies react?
- Monocytes/macrophages
IgG coated red cells will be phagocytized by what effector cells?
M and N are codominant alleles
In the MN blood group system, a person who inherits an "M" allele and an "N" allele expresses both M and N antigens on the RBCs. Which of the following is true?
Difference in immunogenicity
Only 5% of Kell-negative individuals will develop antibodies to Kell if exposed to the Kell antigen. Whereas 50%-70% of Rh(D) negative individuals would produce antibodies to D upon exposure to the D antigen. What is the reason for this?
AB
Reverse grouping showed negative reactions with A1 and B cells. Forward grouping showed positive reactions with A, B, and A,B antisera. What blood type is consistent with these results?
0.89% normal saline
Reverse grouping was performed on an AB person. The blood bank tech observed a very weak agglutination macroscopically. The cells appeared as "stacked coins" under microscopic examination. Which reagent should be added to the tube and recentrifuged in an attempt to resolve the discrepancy?
Naturally occurring
The ABO group antibodies are primarily?
In vitro
The indirect (IAT) antiglobulin test detects which antigen-antibody reactions?
Reverse grouping
Two drops of serum are added to one drop A1 cells, and two drops of serum are added to one drop of B cells; the two tubes are centrifuged. The tubes show reactivity when read macroscopically. This is an example of?
Rh negative
What Rh type does a mother have to be to produce antibodies to Rh(D) from an Rh positive fetus?
IgG
What class of immunoglobulins is capable of crossing the placenta?
A positive result
What does hemolysis represent in an antigen-antibody reaction?
Group O Rh(D)+ red cells coated with anti-D
What does the check cell reagent vial contain?
D-galactose
What immunodominant sugar is responsible for B specificity?
L-fucose
What immunodominant sugar is responsible for H specificity?
Seed extracts that agglutinate human red cells with moderate specificity
What is a lectin?
Elderly patient, immunocompromised, and IgM deficiency
What is a possible explanation for a weak reaction (1+) in a reverse test for ABO grouping?
When the forward grouping results do not match the reverse grouping results
What is an ABO discrepancy?
Removes water molecules, thereby concentrating antibody
What is the action of PEG?
A protein molecule produced in response to an antigen
What is the definition of an immunoglobulin?
Dolichos biflorus
What is the source of anti-A1 lectin?
Ulex europaeus
What is the source of anti-H lectin?
The attraction of negative charges on the surface of the RBC to positive charges in an ionic cloud
What is zeta potential?
5%
What percentage of A2 individuals produce anti-A1?
Adsorption
What test is used to remove antibodies from test serum?
IgG allo and autoantibodies and C3b complement components
What type of globulin does the antiglobulin test detect?
Phenotype
When an individual is said to have blood group A, it refers to the individual's?
Tears, saliva, and milk
Where are ABH substances detected in secretors?
ABO
Which blood group antibodies are known to activate complement leading to intravascular hemolysis?
O
Which blood group contains the highest concentration of H antigen?
H
Which substance must be formed first before A or B specificity is determined?
To ensure that AHG was not neutralized by free globulin molecules
Why are check cells added to all negative reactions in the AHG test?
Calcium is inactivated
Why is EDTA not conducive to complement activation?
It reduces the incubation time
Why is low ionic strength saline (LISS) used in blood banking?
IgM
Anti-A form a group B individual is primarily what class of immunoglobulin?
6 months
At what age do infants begin to produce their own antibodies?
Detecting antigen(s) on an individual red cells via reagent antisera
Forward grouping is defined as?
IgG, C3b, and C3d
What does polyspecific AHG contain?
Bombay
What does the hh genotype refer to?
45%
What percentage of the general population has type O blood?
80%
What percentage of the type A population are A1?
A,H
What substances are found in a group A secretor?
Alloantibodies
Which of the following are produced after exposure to genetically different nonself antigens of the same species?
2 light chains and 2 heavy chains held together by covalent disulfide bonds
Which of the following corresponds to the basic structure of an immunoglobulin?
Antibodies are generally not present at birth
Why is reverse grouping not performed on cord blood specimens?
PEG may cause aggregation of RBCs at 37°C
Why is the 37°C reading omitted when using PEG?