AntiAB

AntiAB is a term used in immunohematology to describe antibodies directed against AB blood group antigens in the ABO system. The AB antigen refers to the combined A and B carbohydrate structures on red blood cells. Antibodies that react with AB antigens would, in theory, recognize both A and B antigens and possibly AB-bearing cells. Such antibodies are described only rarely and are not a routine focus of standard ABO testing.

In practice, most naturally occurring antibodies in the ABO system are anti-A or anti-B, and individuals with type AB blood generally do not produce anti-A or anti-B antibodies. AntiAB antibodies, when present, are considered uncommon alloantibodies or autoantibodies and can complicate transfusion medicine and, less commonly, transplantation or pregnancy. Their clinical significance depends on their ability to react with donor red cells that express A, B, or both antigens, potentially causing hemolytic reactions or transfusion incompatibilities.

Detection of antiAB antibodies relies on specialized serologic workups beyond routine ABO typing. Antibody screening and identification, typically performed with panel cells and indirect antiglobulin testing, are used to determine the specificity of the antibody and to guide compatible blood selection. Transfusion management focuses on avoiding donor units that would be reactive with the patient’s antibody, often requiring detailed antigen profiling of both patient and donor blood.

Overall, antiAB represents a rare serologic finding in the ABO system. When identified, it prompts thorough antibody identification and careful transfusion planning to ensure safety.