Isohemagglutinins
Definition
The naturally occurring antibodies (anti-A and/or anti-B) present in serum from birth without prior transfusion or immunisation. Group A individuals carry anti-B; group B individuals carry anti-A; group O individuals carry both; group AB individuals carry neither.
- Antibody type
- Naturally occurring, no prior exposure needed
- Group A carries
- Anti-B
- Group B carries
- Anti-A
- Group O carries
- Anti-A and anti-B
Common questions
How were isohemagglutinins used in forensic ABO typing?+
The absorption-inhibition and related serological techniques used isohemagglutinin reactions to detect which ABO antigens were present in a dried bloodstain, letting an examiner assign an ABO group to a stain before DNA typing existed.
Why do group AB individuals carry neither antibody?+
Isohemagglutinin production is suppressed against antigens the body itself expresses, since anti-A or anti-B would otherwise attack the person's own red cells. A group AB individual expresses both A and B antigens, so neither antibody is produced.
Related terms
- Agglutination
- Clumping of red cells that occurs when antibodies in serum bind to incompatible antigens on the cell surface, cross-linking cells into visible...
- Antigen
- A molecule recognised by the adaptive immune system through specific binding to an antibody or T-cell receptor. Defined by immunogenicity (capacity to...
- Forensic Serology
- The branch of forensic science concerned with detecting and characterising biological fluids (blood, semen, saliva, vaginal secretions) as evidence in legal proceedings,...
- Glycosyltransferase
- The enzyme encoded by the ABO gene locus that attaches terminal sugar residues to the H antigen chain. Group A transferase adds...
- H Antigen
- A fucose-containing oligosaccharide on red cell surfaces and secreted epithelial cells, produced by FUT1 (on red cells) and FUT2 (in secretions). It...