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?