The hypothesis of immune testing of partners—Friend/foe identification systems in historical perspective

Abstract

The hypothesis of “autoimmune testing” of mating partners assumes the formation of an immune-based individual perception system involving intravital selection of direct or inverse replica of self key antigens or alarm molecules. Such system ensures coordinated changes of the signaling system and system of signal perception as new adaptations appear, which automatically provides for reproductive isolation within a limited number of generations. The presence of the friend/foe identification systems in nearly all living organisms suggests the formation of the mechanisms of autoimmune testing of potential mating partners at the earliest stages of evolution. Possible mechanisms of friend/foe discrimination involving major histocompatibility complex and similar proteins are analyzed in historical perspective—from bacteria to lower chordates.