Alloimmunity in the Gorgonian Coral Swiftia exserta

This study of histocompatibility demonstrates that the gorgonian Swiftia exserta (Coelenterata, Anthozoan) fulfills the minimal functional criteria of cytotoxicity, specificity, and altered secondary response (memory) that characterize an adaptive immune response. All autografts (self grafts) fused, and all allografts (intraspecific grafts) underwent rejection, which is characterized by rapid and progressive blanching, necrosis, and loss of tissue in the immediate contact area. Initial reactions required 7-9 days to produce 1 mm of necrosis, but after a resting period, a second contact at a new tissue area yielded the same reaction in 3-4 days. After primary sensitization, intervals of up to eight weeks still produced a significantly accelerated secondary response. Significant differences between the reaction times of second set and third party allografts demonstrated recognition specificity in these responses. Thus, this is the first report of an adaptive alloimmune response in gorgonians.