The Graft-Versus-Host Reaction in the Snapping Turtle Chelydra Serpentina

Newly hatched snapping turtles, Chelydra serpentina, derived from and separated into New York and Wisconsin populations were injected i.p. with 5 x 100 spleen cells from unrelated adult Wisconsin donors. Separate host groups were maintained at 30 C and 20 C. The greatest incidence of lethal graft-versus-host (GVH) reactivity (73%) occurred in the 30 C Wisconsin to New York combination. One-half of the host animals in this group died of an acute GVH reaction, which was manifested by weight loss, softening of the shell, and severe splenomegaly. Death ensued within 1 week of injection. In the same combination, only a few cases of acute GVH reactivity occurred in the 20 C group. Of the animals that died (35%), chronic GVH reactions were prevalent. In the Wisconsin to Wisconsin combination there was a lesser incidence of mortality, 48% at 30 C and 19% at 20 C. Most of these showed chronic GVH reactivity. Histo-pathological changes in the host spleens were detected in the affected animals. Among the host animals that survived more than 120 days, there was a wide distribution of weight patterns, from continual weight gain (no detectable GVH reactions) to a very slow loss, sometimes followed by weight gain and recovery (weak GVH reactions). The spectrum of GVH reactions is probably attributable to a diversity of transplantation antigens leading to multiple histoincompatibility differences in outbred turtle populations. These genetic differences are greater between subjects of separate geographic populations than between those within the same population, suggesting natural regional inbreeding. Immunologically mature turtles (4 months old) were not affected by the spleen inocula. Spleen cells from an adult xenogeneic donor, Chrysemys picta, were ineffective in causing GVH reactions in newly hatched snapping turtle hosts.