Effect of thymectomy on development of Lucké renal adenocarcinomas in virus-infected leopard frog tadpoles.

Thymectomy of very young leopard frog (Rana pipiens) larvae dramatically reduced in vitro lymphocyte responses to the nitrogen phytohemagglutinin-P and prolonged survival of Lucké tumor alloimplants. However, tumor incidence in premetamorphic or metamorphosing frogs that had received injections as embryos of Lucké tumor herpesvirus (LTHV) was the same in thymectomized and normal immunocompetent animals. This result suggests that T-cell-mediated cytotoxicity does not prevent development of Lucké tumors in immunocompetent larvae and that if tumor-specific transplantation antigens appear, they may induce tolerance rather than destructive immunity in normal LTHV-injected larvae.