title: Mechanism of mastocytoma-mediated suppression of lymphocyte reactivity.
abstract: Previously we have shown that mitomycin-treated P-815 (H-2d) cells (P-815m) inhibit the in vitro response of C57BL/6 spleen cells to mitogens and DBA/2 alloantigens. The present data indicate that P-815m cells also inhibit the response of C57BL/6 spleen cells to AKR (H-2k)-stimulating cells and that the inhibition does not appear to be the result of crowding. Subpopulations of spleen cells obtained by density gradient centrifucation or after renoval of glass-adherent cells are all sensitive to the inhibitory effects of P-815m. We also show that P-815m cells appears to operate both in vitro and in vivo. The experiments characterize the suppression of MLC reactivity by cell-free preparations of sonicated P-815 mastocytoma cells. The results suggest that the inhibition is not removed by ultracentrifugation, ultra-violet irradiation, or dialysis of the sonicate. P-815 sonicates subjected to chloroform extraction, heating at 56 degrees C, 0.1 mu filtration, or treatment with anit-minute virus of mice serum are still inhibitory. This inhibition is resistant to RNAase treatment but destroyed by pronase. P-815 sonicate suppresses the response of C57BL/6 spleen cells to both DBA/2 and AKR-stimulating spleen. Inhibition of MLC reactivity is only seen if P-815 sonicate is added within the first 48 hr after the initiation of culture. These results indicate that the inhibition of MLC by sonicates of P-815 cells is due to a nondialyzable protein whose effects are not H-2 restricted and are acting on the early phase of sensitization.
mesh_terms: D000818:Animals; D002469:Cell Separation; D002474:Cell-Free System; D002725:Chloroform / Q000494:pharmacology; D003956:Dialysis; D005260:Female; D005374:Filtration; D006358:Hot Temperature; D007111:Immunity, Cellular; D007165:Immunosuppression Therapy; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D008264:Macrophages; D008297:Male; D012515:Mast-Cell Sarcoma / Q000276:immunology*; D051379:Mice; D008806:Mice, Inbred AKR; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA
chemical_list: D002725:Chloroform