INVITRO STUDIES OF RABBIT IMMUNE SYSTEM .6. RABBIT ANTI-MOUSE CYTOTOXIC T EFFECTOR CELLS ARE INHIBITED BY ANTI-RABBIT T-CELL SERUM IN ABSENCE OF COMPLEMENT

Abstract

Xenogeneic rabbit anti-mouse cell-mediated cytotoxic activity was generated by culturing lymphoid cells from mesenteric lymph nodes (MLN), spleen or peripheral blood of rabbits primed 2-8 wk earlier with mouse tumor or spleen cells. MLN cells, which provided the best source of activity after being cultured with 5-10 .times. 106 mitomycin C-treated mouse spleen cells for 4-6 days, produced 30-90% specific isotope release after 4-7 h incubation with 15Cr-labeled tumor target cells. Xenogeneic cytotoxic activity was primarily H-2 specific and could not be blocked by immune complexes but was abrogated by treatment with goat anti-rabbit thymocyte serum plus complement (ATS + C) before of after culture. The activity appeared to be mediated by cytotoxic T [thymus-derived] lymphocytes (CTL). ATS without C abrogated cytotxic activity when included in the CTL assay at concentrations of 5-15 .mu.l/107 effector cells. The inhibitory activity of ATS was directed to the rabbit effector population and was absorbed completely by rabbit thymocytes. Antisera to mouse T cells with comparable cytolytic activity in the presence of C did not inhibit murine allogeneic CTL.