Expression of differentiation and murine leukemia virus antigens on cells of primary tumors and cell lines derived from chemically induced lymphomas of RF/J mice.

3-Methylcholanthrene (MCA) skin painting rapidly induced a 100% incidence of thymic lymphomas in RF/J mice. Tumors developed exclusively in cells of the T-lymphocyte lineage and displayed the surface phenotype: Thy-1+, Lyt-1+, Lyt-2+, Qa-1+, H-2K+, H-2D+, TL-, Ig-, Ia-. This phenotype resembled that of cortisone-resistant, medullary thymocytes, whereas the phenotype of spontaneous AKR thymomas resembles that of cortisone-sensitive, cortical thymocytes. The phenotype differed very little from one tumor to another and was maintained during syngeneic passage in vivo and adaptation to growth in culture. Infectious ecotropic murine leukemia virus (MuLV) was produced in a minority of primary tumors and cell lines, but no xenotropic or mink cell focus-inducing virus (MCF) MuLV production was reliably detected. MuLV-related antigen expression on normal thymocytes increased in an age-dependent manner, and levels on thymoma cells were similar to those on thymocytes from age-matched normal controls. MuLV nonproducer tumor cells expressed few or no epitopes of AKR ecotropic gp70, but they were positive when tested with an antiserum prepared against MCFenv glycoprotein.