Immunohematology Exam 1

• ABO antigens are inherited through a codominant fashion.
• Acidified human anti-B can determine if a patient has acquired B antigen.
• Having both A and B alleles presents type AB.
• The O gene is an amorph or silent gene (no product).
• The locus of the ABO gene is on the long arm of chromosome 9.
• H codes for L-fucosyltransferase which adds the immunodominant sugar L-fucose.
• Wharton’s jelly is a gelatinous substance on cord blood that requires 4-6x cell washing before forward type and cannot do reverse type still because the jelly is in the plasma.
• Fetus begins producing antigens starting at week 5 of fetal life, increasing their production as they grow.
• By birth, fetus has about half the antigens they will produce.
• A codes for N-acetylgalactosaminyl-transferase which adds the immunodominant sugar N-acetylgalactosamine to the base O-antigen.
• ABO antibodies rise shortly after birth as a result of exposure to the outside world.
• Rouleaux is an increased protein in the plasma specifically immunoglobulin that can be mistaken for agglutination.
• ABO antibodies weaken with age.
• Testing patient sample at lower temperatures enhances the reaction.
• Under 6 months, children have not developed many antibodies, making the reverse-type unreliable.
• Concentration of H antigen on the surface of the RBCs of common blood groups: O> A2> B > A2B > A1> A1B.
• Acquired B can result from bacterial infections from GNB, and the deacetylase enzyme can make patients A antigens appear B-like.
• B codes for D-galactosyltransferase which adds the immunodominant D-galactose to the base O-antigen.
• The most common ABO types in the US are: O, A, B, AB.
• Rh + is more common than Rh- each group.
• The H gene is dominant to h.
• You need at least one H (Homozygous dominant or heterozygous) to produce the transferase that makes H substance.
• Without H substance, you cannot add the A and B antigens.
• People who do not make H substance have the Bombay phenotype and therefore make antibodies to H and can only be transfused with other Bombay phenotype blood.
• Ulex europeus lectin reacts with H antigen. Bombay patients will be negative.
• Para-Bombay: Some individuals with the secretor gene can produce H substance in their plasma and other body fluids.
• Para-bombay: H substance can float onto their red cells causing weak reactions.
• Normal AB patients possess both an A and a B allele.
• CISAB arises from a genetic mutation of the ABO gene that allows them to code the transferase enzyme for both A and B.
• Subgroups of A include A1 and A2.
• A2 can produce anti-A1, causing a discrepancy in the reverse type where the patient will react to a cells.
• A2 cells carry less antigen than A1, causing them to react with Ulex europeus anti-h lectin.
• Plant lectin from Dolichos biflorus can differentiate A1 from A2, agglutinating A1 cells and not A2.
• There are other A subgroups but they are clinically insignificant.
• Newer Anti-A reagents are more sensitive to A2 but previously we would use Anti-AB as it picks up on A2 better.