INFECTION OF MURINE MACROPHAGES WITH TOXOPLASMA-GONDII IS ASSOCIATED WITH RELEASE OF TRANSFORMING GROWTH-FACTOR-BETA AND DOWN-REGULATION OFEXPRESSION OF TUMOR-NECROSIS-FACTOR RECEPTORS

Toxoplasma gondii is capable of invading and multiplying within murine peritoneal macrophages. Previous studies have shown that treatment of macrophage monolayers with recombinant gamma interferon but not tumor necrosis factor (TNF) is associated with intracellular killing of T. gondii by macrophages. Furthermore, infection of macrophages with T. g ondii prevents their stimulation for mycobactericidal activity by TNF. Since transforming growth factor beta (TGF-beta) is known to suppress a number of functions in macrophages, we investigated the influence o f infection with T. gondii on macrophage TNF receptors and on producti on of TGF-beta. Infection with T. gondii was associated with increased production of TGF-beta and downregulation of TNF receptors. This effe ct was observed early after infection and was partially inhibited by a nti-TGF-beta1 antibody.