No abstract

Summary Lymphocytes generated in mice by infection with Salmonella enteritidis 11RX release interleukin 2 and macrophage activation factor upon subsequent in vitro culture with bacterial antigens. Lymphokine release requires the co‐culture of non‐adherent sensitized Lyt 1+2‐ T cells and adherent metabolically active accessory cells; the interaction between these two populations is restricted by the H‐2 I‐A locus. Following systemic immunization with the 11RX strain, the two lymphokines are produced in parallel by peritoneal cells, whereas spleen cells primarily release macrophage activation factor.

Summary Intraperitoneal injection of (BALB/c X C57BL/6) Fl mice with live, but not killed Salmonella enteritidis 1 lRX (1 lRX) induced T cells in the spleen and peritoneal cavity which were able to proliferate in vitro in response to two different forms of 1 lRX antigens. The majority of cells which proliferated were L3T4+ T cells and most of the response was restricted by the I-A locus of the H-2 major histocompatibility complex, although a smaller K region restricted response was also detected. T cells able to respond to 1 lRX antigens could only be demonstrated when non-adherent lymphoid cell suspensions from immunized mice were used, and usually a limited response was obtained unless smalt numbers of adherent cells present in normal peritoneal cell suspensions were added. Cells cultured in vitro for 3 days were able to mediate local transfer of delayed type hypersensitivity and secondary immunization did not enhance the reactivity of responding cells to 11RX antigens.

Stntunny. Aniigcn-and Concanavalin A-induccd culture supematanis have been reported to contain inhibitors of interleukin 2 (11.2) activity which necessitate conccniration of samples over Amlcon membranes prior to lymphokine assay. However, since we found this to be unnecessary, we have rc-cvatuatcd the effects of Amicon and millipore membranes upon the lymphokine litres of such supernatants. Our findings do not support the notion of an IL2 inhibitor, but indicate that tymphokinc levels can l>e dramatically reduced as 3 consequence of millipore filtration.

An adoptive local transfer system has been used to study the mediators of delayed-type hypersensitivity induced in mice by infection with Salmonella enteritidis 11RX. The cells which transfer this state of hypersensitivity to untreated recipients are nonadherent T lymphocytes with the surface phenotype Lyt 1+2-, and successful transfer requires compatibility at the I-A subregion of the H-2 complex. In these and other respects these cells are indistinguishable from those previously found to be responsible for in vitro lymphokine release upon culture with 11RX antigens.