Analysis of a murine B cell lymphoma, CH44, with an associated non-neoplastic T cell population. I. Proliferation of normal T lymphocytes is induced by a secreted product of the malignant B cells.

A non-neoplastic T cell population associated with a murine monoclonal B cell malignancy, CH44, was analyzed. Immunofluorescence on cell suspensions and immunoperoxidase staining on tissue sections using monoclonal antibodies to the antigens Thy1.2, Ly-1, L3T4, and Lyt-2 confirmed the presence of both TH (Ly-1/L3T4+, Lyt-2-) and Tc/s (Ly-1/L3T4-, Lyt-2+) T cell subpopulations. The non-neoplastic T cells were present in both a 0.6 and 2.1 g CH44-bearing spleen. T cells, not normally in liver in significant numbers, were found in liver tissue when the CH44 tumor cells were present. These data implied an active proliferation of the T cell populations within tissues containing the malignant B cells. Supernatant from an in-vitro-adapted cell line of CH44 (CH44.LX) was tested for its ability to induce proliferation of normal murine splenocytes and thymocytes. As assayed by tritiated thymidine incorporation, both spleen and thymus cells proliferated in the presence of CH44.LX supernatant. Although supernatant from two of nine other B cell lines was able to stimulate the proliferation of spleen cells, only CH44.LX could induce proliferation of thymus cells. Supernatant from the seven other B cell lines and three hybridomas had no measurable effect on either splenocytes or thymocytes in this assay. It is hypothesized that the presence of a non-neoplastic proliferating T cell population associated with a neoplastic B cell lymphoma during in vivo passaging of the tumor is the result of effects derived from a secreted product of the malignant B cells. Whether the T cells have any effect on the growth of the malignant B cells is not known.