Lecture 2 Flashcards
Which group is most know for H antigen?
Type O
Do type A1 have H antigen?
Yes but not a lot.
in the presence of the A1 gene, almost all of the H antigen is converted to A1
anti-H
a naturally occurring IgM cold agglutinin that reacts best below room temperature
Subgroup of B
rare and less frequent than A subgroups
initially identified by variability of reactions with anti-B and anti-A,B
Bombay Phenotypes
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
What can be transfused with Bombay phenotypes?
Can only be transfused with blood from another Bombay (Oh)
H-Deficient Phenotypes
rare phenotypes in which the RBCs are completely devoid of H antigens or that have small amounts of H antigen present
h allele
very rare and does not produce α-2-L-fucosyltransferase necessary of formation of the H structure
ABO Discrepancies
Occur when unexpected reactions occur in the forward and reverse grouping
Group I discrepancies
unexpected reactions in the reverse grouping due to weakly reacting or missing antibodies. (Most common type)
What could cause Group I discrepancies?
patient has depressed antibody production or cannot produce the ABO antibodies
Group I discrepancy populations
Babies, elderly
Patients with leukemias
Patients using immunosuppressive drugs
Patients with bone marrow transplantations
Resolution of Common Group I Discrepancies
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
Group II Discrepancies
Associated with unexpected reactions in the forward grouping due to weakly reacting or missing antigens. (Least frequently encountered).
Causes Group II Discrepancies
Subgroup of A (or B) may be present
Leukemia’s may yield weakened A or B antigens
Hodgkin’s disease
“Acquired B” phenomenon
Resolutions of Group II Discrepancies
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
Group III Discrepancies
Discrepancies are between forward and reverse groupings caused by protein or plasma abnormalities and result in rouleaux formation, or pseudo agglutination
Group III Discrepancies Causes
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
Group III Discrepancies Resolution
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
Rouleaux
or stacking of erythrocytes that adhere in a coin-like fashion giving the appearance of agglutination
Group IV Discrepancies
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
Group IV Discrepancies Resolution
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
