Abstract
Lymphoid cells from normal and immunized BALB/c mice could be stimulated in vitro by syngeneic plasma cell tumors (PCT) using a one-way mixed lymphcoyte tumor interaction (MLTI) assay. The reactivity of normal spleen cells to syngeneic PCT contrasted with an absence of response to a number of other tumors. Maximal responses of normal cells to PCT were found to occur 5 days after the initiation of the cultures at an optimal responding:stimulating cell ratio of 1:2. MLTI activity of normal cells could not be blocked or enhanced by PCT myeloma protein products indicating that MLTI reactivity was directed against non-idiotypic cell surface determinants. Lymphoid cells from immunized mice demonstrated increased MLTI responses to cells of the immunizing tumor but not to other PCT, indicating that the post-immunization MLTI responses were primarily to individual rather than shared tumor cell surface antigens. Activity of both normal and immunized spleen cells was found to involve thymusderived lymphocytes. The persistence of residual MLTI activity after treatment with anti-θ serum and complement, however, implicated participation of non-θ antigenbearing cells in MLTI reactivity. From these data, we conclude that lymphoid cells from un-immunized mice are capable of T cell-dependent reactivity to syngeneic PCT-associated antigens and that elevations in these reactivities after immunization may reflect specific cellular immune responses.
Footnotes
This work was supported by National Institutes of Health Grant CA12800 and Grant 5 T01 AI 00431 in Clinical and Fundamental Immunology.
