Allogeneic polymorphism and alloimmune memory in the coral, Montipora verrucosa

Populations of the coral Montipora verrucosa exhibited very extensive allogeneic polymorphism revealed by parabiotic incompatibility amont 890 different pairings of colonies (clones) without exception. More than 1,400 reciprocal histoincompatibilities were actually recorded because bilateral cytotoxicity was observed among most of the the alloparabionts tested. This "uniqueness of the individual" in terms of cell surface histocompatibility (H) markers is manifest in the whole spectrum of possible incompatibilities from strong to moderate to weak. The directionality, severity, and rate of rejection were mainly determined by the genetic constitutions of the interclonal parabionts. Allograft reaction times were closely temperature dependent and inversely related to the strength of the H barrier. Heightened alloimmunity or early memory was demonstrable after only 2 days of presensitization and became maximal after 4 to 8 days. After prolonged primary immunization, potent alloimmune memory persisted for 4 weeks, but disappeared after 8 to 16 weeks. Immunological primitiveness in corals may therefore be reflected in the lack of long-lived memory as found among vertebrates.