Tissue transplantation immunity in the adult newt, Diemictylus viridescens. III. The effects of X‐irradiation and temperature on the allograft reaction

Graded dosages of x‐irradiation from 500r to 3000r inhibited destruction of Diemictylus viridescens allografts at 23 ± 0.5°C for at least as long as the survival time of the hosts (up to 35 days). Lymphocytes were observed in 20% of the grafts whose hosts received 500r and 1000r but they were present in far weaker concentrations than seen in any control grafts at all stages of rejection. No lymphocytes were evident in any grafts on hosts irradiated with 1500r, 2000r, and 3000r. The effects of various temperatures on allograft rejection in the newt were also examined. There was no difference in the mean survival times of grafts maintained at 30°C and 23°C. At 20°C, however, hemostasis and hemorrhaging were significantly delayed by a factor of 1.6 and 1.7 times, respectively, when compared with the findings at 23°C. At 10–15°C, no hemostasis or hemorrhaging were displayed for 191 days after transplantation. Lymphocytes, however, were apparent in very low concentrations in the tissues of some of the grafts and localized destruction of a few melanophores were noted. Two grafts maintained at 10–15°C for 155 days and then transferred to 20°C were completely destroyed within 36 days. This destruction was more rapid than for grafts initially maintained at 20°C.