H antigen

H antigen can refer to one of various types of antigens having diverse biological functions. H antigen is located on the 19th chromosome in humans, and has a variety of functions and definitions as follows:

  • Also known as substance H, H antigen is a precursor to each of the ABO blood group antigens, apparently present in all people except those with the Bombay Blood phenotype[1] (see Hh antigen system)
  • Histocompatibility antigen, a major factor in graft rejection. Even when Major Histocompatibility Complex genotype is perfectly matched, can cause slow rejection of a graft.[2]
    • major H antigens "encode molecules that present foreign peptides to T cells"[2]
    • minor H antigens "present polymorphic self peptides to T cells".[2] Includes, e.g. the H-Y antigen
  • a bacterial flagellar antigen[3]
"H substance" redirects here. The term also historically referred to histamine.

References
  1. Science Of Biogenetics. "Do you Know Bombay Blood Group".
  2. Janeway, Charles A. (2001). Immunobiology the immune system health & disease (5. ed.). New York: Garland. ISBN 978-0-8153-3642-6. Retrieved 16 December 2013.
  3. Farlex. "antigen". The Free Dictionary. Retrieved 16 December 2013.


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