ImmunohematologyBlood Banking (Group 1)
Blood Group Antigen & Antibody
Blood Group Antigen Antibody Ig
A A B
Predominantly IgM & small quantities of
IgG
B B A
AB A, B NEITHER
O NEITHER A, B
ABO Antibodies
• Individuals normally produce Ab directed against the A &/or B Ag(s) absent from their RBCs.-NATURALLY OCCURING, because they are produce without any exposure to RBCs.
• Produce strong direct agglutination reactions during ABO testing
ABO Antibodies
• Are initiated at birth, but titre are too low until 3-6 months– Test before these months are considered invalid
because of maternal origin of Ig
• 5-10 years, Ab production peaks then declines later in life
• Elderly people usually have lower levels of Anti-A & Anti-B; therefore Ab may be undetectable in the reverse grouping.
ABH Antigens
• Results from the interaction of genes at three separate loci (ABO, Hh & Se).
– Produce specific glycosyltransferases that add sugars to a basic precursor substance.
– A, B, & H Ag are formed from the same basic precursor material paragloboside or glycan
ABH Antigens
• on the RBC are constructed on oligosaccharide chains of a type 2 precursor substance
• Developed early in fatal life but do not increase much in gestational period.
• 2-4 years of age• Phenotypic expression may vary in race, genetic
interaction and disease states– Expression of A & B Ag on the RBCs is fully
developed and remains constant throughout life
ABH Antigens
• H- Antigen– Precursor structure on which A & B Ag are
made. – H gene must be inherited to form ABO Ag on
the RBCs whereas Se for Ag in secretions.
Blood group Complement (C)
• Is a complex group of over 20 circulating and cell membrane proteins that have a multitude of functions within the immune response.
• Primary roles include direct lysis and assisting of opsonization and production of peptide fragment split products which play roles in inflammatory responses.
• can also have detrimental effects for the host; it contributes to inflammation and tissue damage and it can trigger anaphylaxis
• Complement components circulate in inactive form as proenzyme
Blood group Complement
• Complement proteins are activated in a cascade of events through three main pathways:– Classical– Alternative– Lectin– Then eventually goes to MAC (Membrane
Attack Complex)
Blood group Complement
Blood group Complement
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