Temperature but not season affects the transplantation immunity of anuran amphibians.

The effects of ambient temperature (22 degrees C/10 degrees C) and season (summer/winter) on anuran skin allograft and xenograft rejection was tested in frogs (Rana temporaria and R. esculenta) and toads (Bufo bufo, Bombina variegata, and Bombina bombina). Mean graft survival times were significantly prolonged at the low temperature in a species-specific manner, the edible frog (R. esculenta) being the most sensitive and the common toad (Bufo bufo) relatively resistant. Allografts were more temperature-dependent than xenografts; in the latter case, temperature sensitivity was specific to each donor-host combination. Rejection of second-set grafts in R. esculenta was accelerated both in warmth and in cold, but second-set grafts were less temperature-sensitive than sensitizing ones. Both in summer and in winter, R. esculenta rejected allografts promptly at 22 degrees C but slowly at 10 degrees C. In both seasons, Bombina variegata kept at 22 degrees C rejected allografts in a chronic manner. This indicates that amphibian transplantation immunity depends on the donor-host genetic disparity and ambient temperature but is independent of season.