Characteristics of Soluble T-Cell Derived Factor(s) which Can Induce Non-immune Murine Macrophages to Exert Anti-toxoplasma Activity

Cell-free supernatants from cultures of specifically stimulated toxoplasmaimmune T-cells contain factor (or factors) that can in vitro arm non-immune thioglycollate stimulated mouse peritoneal macrophages (MPM) to exert antitoxoplasma activity (anti-toxoplasma arming factor(s) = ATAF). ATAF was not demonstrated in supernatants from cultures of concanavalin A stimulated spleen lymphocyte cultures or specifically stimulated listeria-immune T-cell cultures, although they contained macrophage migration inhibitory factor (MIF). It was found that toxoplama-immune T-cells incubated together with specific antigen for 16 hrs, but not those incubated for 1 or 6 hrs, yield ATAF containing supernatants. Furthermore, production of ATAF in T-cell supernatants was an active temperature dependent process, since it required glucose for its production and appeared in cultures incubated at 37 °C but not at 4°C. ATAF failed to appear in supernatants of toxoplasma-immune T-cells when cultured with specific antigen in presence of actinomycin D, emetine or puromycin but colchicine had no effect on its production. ATAF activity was found to show no genetic restrictions, in that it could induce anti-toxoplasma activity in MPM from mouse strains genetically unrelated to the strain which donated immune T-cells for obtaining ATAF. ATAF could be absorbed out with normal, but not with trypsinized MPM. Neither normal nor trypsinized lymphocytes could absorb out ATAF from active supernatants. Enzyme treatments revealed that ATAF was resistant to DNase and RNase but was inactivated by exposure to trypsin or heating at 58 °C for 30 min. Apparently, ATAF in crude supernatants could be stored at -70 °C for 4 months without loss of its activity. Experiments using «Diaflo» membranes suggest that molecular size of ATAF in crude supernatants lies in the range 50,000–100,000. The above findings have extended our previous observations and further defined the characteristics of ATAF.