Induction of simian virus 40 transplantation immunity in hamsters by gel-purified SV40 large T antigen.

Simian virus 40 (SV40) large T antigen and p53 cellular protein were isolated from an SV40-transformed hamster cell line by immunoprecipitation with anti-T sera and purified by sodium dodecyl sulfate-gel electrophoresis. These two protein were tested in hamsters for the presence of SV40 transplantation rejection antigenic sites by in vivo transplantation rejection assay. The large T antigen immunized the hamsters against a challenge of SV40 tumor cells and the protected animals generated cytotoxic spleen cells.

Evolution of DNA polymerase alpha, beta and terminal deoxynucleotidyl transferase in hamster lymphoid populations during the development of different types of tumors.

We followed the evolution of DNA polymerase alpha, beta and terminal deoxynucleotidyl transferase (TdT) in the thymus, spleen and bone marrow of tumor bearing hamsters. Tumors were induced by spontaneously transformed fibroblasts (EHB), by SV40 (ZD) or by 20-methylcholanthrene (MCH2) transformed fibroblasts. We have shown that, in the thymus, the TdT activity of the various tumor bearing hamsters is generally inferior to the TdT activity of the control.

Cyclophosphamide induction of splenic suppressor cells in hamsters.

Injection of hamsters with a single sublethal dose of cyclophosphamide induced splenic atrophy followed by considerable hypertrophy. During the splenomegaly phase, the in vitro reactivity of spleen cells to concanavalin A (ConA) or protein A (ProtA) was decreased. The spleens of 6-8-month old animals contained cells able to suppress the in vitro reactivity of normal lymphocytes to ConA or ProtA.