MODULATORY EFFECT OF DALTONS LYMPHOMA-CELLS ON THE PRODUCTION OF REACTIVE NITROGEN INTERMEDIATES, INTERLEUKIN-1 AND TUMOR-NECROSIS-FACTOR BY MURINE PERITONEAL-MACROPHAGES

The effect of Dalton's lymphoma (DL) cells on the production of reacti ve nitrogen intermediates (RNI), interleukin-1 (IL-1) and tumor necros is factor (TNF) by murine peritoneal macrophages was investigated. Tre atment of macrophages with LPS resulted in significant enhancement in the production of RNI, soluble and membrane-associated IL-1 and TNF. A significant inhibition in the production of RNI and IL-1 was observed when the macrophages were coincubated with DL cells whereas TNF produ ction was enhanced. Incubation of macrophages in the presence of DL ce lls alone even in the absence of LPS could induce production of TNF le vel comparable to that of LPS treated macrophages. Paraformaldehyde fi xed DL cells and DL cell conditioned medium could also inhibit RNI pro duction by macrophages. On the other hand pre-exposure of macrophages to viable DL cells or DL cell-conditioned medium prior to treatment wi th LPS could prime the macrophages for enhanced production of RNI. Thi s study indicates that the regulatory effect of lymphoma cells on macr ophage activation may have relevance ot the host defence against tumor s.