The induction of immunoblastic T cell sarcomas by virus-transformed prothymocytes.

The ontogeny of thymus-dependent lymphoid tumors induced by murine sarcoma-murine leukemia virus (MSV-MuLV) was investigated. Tumors that developed in spleens of infected mice 6 or more months after the injection of virus were diagnosed as immunoblastic T cell sarcomas. Cells derived from the tumors and established as a continuous cell line expressed the thymus leukemia (TL), brain-associated theta (BAT), and Qa2 cell surface antigens but lacked either the Ly 1 or Ly 2, 3 mature T cell differentiation antigens. In addition, the tumor cell expressed c type viral antigens, and had receptors for the lectin peanut agglutinin. The tumor cells were inert when tested for their capacity to respond in several functional T cell assays. Taken together, these data support the hypothesis that the primary target of malignant transformation by MSV-MuLV is a prothymocyte.