[Differential expression of relevant Rous sarcoma tumor antigens in cultured cells]

Chickens bearing tumours induced by Rous sarcoma virus (RSV) are able to mount a cellular immune response against antigens associated with these neoplasms. Cultured Rous sarcoma (RS) cells, derived from the wings of chickens bearing tumors induced by RSV, were consistently more susceptible in cytotoxicity assays to killing by the splenic lymphocytes of RS-bearing chickens than were chicken embryo fibroblast (CEF) cells which had been transformed in vitro by RSV. In contrast, extracts (3M KCI-derived) and supernatant fluids of transformed CEF were equally or more capable of eliciting blastogenic responsiveness in circulating lymphocytes of birds with tumors than were similar extracts and supernatant fluids obtained from cultured RS cells. As measured by lymphocyte stimulation, the expression of this anti-tumour response was in some cases only short-lived, and varied between animals in terms of time following inoculation with RSV. These findings point to a differential expression of relevant RS-tumour antigens in these various cell types, and indicate that the use of various experimental techniques may yield quite different results.