What is "isoantibodies"

Isoantibodies (formerly called alloantibody) are antibodies produced by an individual against isoantigens produced by members of the same species. In the case of the species Homo sapiens, for example, there are a significant number of antigens which are different in every individual. When antigens from another individual are introduced into another's body, these isoantibodies immediately bind to and destroy them.

One common example is the isohaemagglutinins, which are responsible for blood transfusion reactions. This may subjectuvely differ from the term ' natural' antibodies or simply 'antibodies' as the former arise due to antigenic stimulation where as the latter seem to arise from genetic control without apparent antigenic stimulation.