Lecture 2

Question 1

Which group is most know for H antigen?

Answer 1

Type O

Question 2

Do type A1 have H antigen?

Answer 2

Yes but not a lot.
in the presence of the A1 gene, almost all of the H antigen is converted to A1

Question 3

anti-H

Answer 3

a naturally occurring IgM cold agglutinin that reacts best below room temperature

Question 4

Subgroup of B

Answer 4

rare and less frequent than A subgroups
initially identified by variability of reactions with anti-B and anti-A,B

Question 5

Bombay Phenotypes

Answer 5

the inheritance of a double dose of the h gene producing the very rare genotype hh
As a result ABO cannot be expressed
ABH antigens can not be formed as there is no H antigen made
Anti-A, anti-B, anti-A,B and anti-H present in the serum

Question 6

What can be transfused with Bombay phenotypes?

Answer 6

Can only be transfused with blood from another Bombay (Oh)

Question 7

H-Deficient Phenotypes

Answer 7

rare phenotypes in which the RBCs are completely devoid of H antigens or that have small amounts of H antigen present

Question 8

h allele

Answer 8

very rare and does not produce α-2-L-fucosyltransferase necessary of formation of the H structure

Question 9

ABO Discrepancies

Answer 9

Occur when unexpected reactions occur in the forward and reverse grouping

Question 10

Group I discrepancies

Answer 10

unexpected reactions in the reverse grouping due to weakly reacting or missing antibodies. (Most common type)

Question 11

What could cause Group I discrepancies?

Answer 11

patient has depressed antibody production or cannot produce the ABO antibodies

Question 12

Group I discrepancy populations

Answer 12

Babies, elderly
Patients with leukemias
Patients using immunosuppressive drugs
Patients with bone marrow transplantations

Question 13

Resolution of Common Group I Discrepancies

Answer 13

Enhance weak or missing reaction in the serum by incubating patient serum with reagent A1 and B cells at r.t. for 15-30 minutes
mixture cans can be incubated at 4oC for 15 to 30 minutes
An auto control and O cell control must always be tested concurrently with the reverse typing when trying to solve the discrepancy

Question 14

Group II Discrepancies

Answer 14

Associated with unexpected reactions in the forward grouping due to weakly reacting or missing antigens. (Least frequently encountered).

Question 15

Causes Group II Discrepancies

Answer 15

Subgroup of A (or B) may be present
Leukemia’s may yield weakened A or B antigens
Hodgkin’s disease
“Acquired B” phenomenon

Question 16

Resolutions of Group II Discrepancies

Answer 16

Similar to group I
pseudo-B antigen is formed at the expense of the A1 antigen and disappears after recovery
Reactions of the appropriate anti-serum with these acquired antigens demonstrates a weak reaction, often yielding a mixed-field appearance

Question 17

Group III Discrepancies

Answer 17

Discrepancies are between forward and reverse groupings caused by protein or plasma abnormalities and result in rouleaux formation, or pseudo agglutination

Question 18

Group III Discrepancies Causes

Answer 18

Elevated levels of globulin from multiple myeloma,
Waldenstroms macroglobulinemia,
advanced cases of Hodgkin’s lymphoma
Elevated levels of fibrinogen
Plasma expanders
Wharton’s jelly in cord blood samples

Question 19

Group III Discrepancies Resolution

Answer 19

Cell grouping can be accomplished by washing in saline
Washing cord cells 6 to 8 times with saline should alleviate spontaneous rouleaux due to Wharton’s jelly

Question 20

Rouleaux

Answer 20

or stacking of erythrocytes that adhere in a coin-like fashion giving the appearance of agglutination

Question 21

Group IV Discrepancies

Answer 21

Discrepancies between forward and reverse groupings
due to cold reactive autoantibodies in which RBCs are so heavily coated with antibody that they spontaneously agglutinate, independent of the specificity of the reagent antibody

Question 22

Group IV Discrepancies Resolution

Answer 22

incubate patients RBCs at 37oC for a short period, then wash 3x with 37oC saline and retype
If not resolved – treat with 0.01 M dithiothreitol (DTT) to disperse IgM-related agglutination