The ABH System & Secretor Status

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Created by
Jayna Ramesh

Cards (10)

  • Establishing secretor status is helpful when trying to determine an ABO blood type of an individual whose red cell antigens are poorly developed or missing (e.g. weak subgroups, leukemia, other malignancy, discrepancies between forward and reverse groupings, etc)
  • Secretor vs non-secretor
    • secretor
    • the portion of the population that is heterozygous (Se/se) or homozygous (Se/Se) for the secretor gene, which is inherited independently of the ABO system
    • it classifies an individual as a secretor since his red cell antigens are secreted into body fluids
    • non-secretor
    • genotype se/se
    • have expression of ABH antigens on red cells, but do not contain them in body fluids
  • Secretor status
    • presence of ABH antigens in secretions
    • controlled by the secretor gene Se
    • Se gene is inherited separately from ABH
    • Se is dominant over se
    • therefore Sese or SeSe results in the presence of H antigens in secretions
    • In US, 78% secretors (homo/hetero) and 22% non-secretor (homo)
  • secretor gene
    • the secretor gene controls only presence or absence of H substance in body secretions
    • it does not affect the presence of H substance of red blood cells
    • if you have A or B transferases and the secretor gene, you will have A and B antigens in secretions
  • Secretor genes
    • Se/Se or Se/se - fucosyltransferase changes fucose to H substance in body fluids only
    • Fucoslytransferase changes fucose to precursor substances (H substance) that can then be changed to A or B antigens
    • If a person has an A gene, can now make A substance in body fluids
    • If a person has a B gene, can not make B substance in body fluids
  • If a person has type O, will only have H substance in secretions
  • No Se means no substance in body fluids
  • se/se will not have H substance in body fluids, so regardless of A and B genes will not have A and/or B substances in body fluids
  • How do we test for it?
    • can test for antigens, using anti-sera, but instead we usually do a neutralizatioN
    • cannot see antigen-antibody reactions in secretions
    • we can determine presence of A and B antigens on surface of RBCs because RBCs are agglutinated by antibodies in vitro, we can see agglutination as cells are large
    • this isn't the case with A and B antigens floating alone in body fluids
  • Neutralization is a technique used to determine the presence of ABH antigens in body fluids