Proliferative signals for suppressor T cells. Helper cells stimulated with pokeweed mitogen in vitro produce a suppressor cell growth factor.
To define molecular signals elaborated by inducer populations supporting growth or differentiation of T8+ cells, we collected supernatants of pokeweed mitogen (PWM)-stimulated cultures depleted of T8+ cells. When added to purified T8+ cells, these supernatants caused significant proliferation. PWM plus interleukin 2 (IL-2) in amounts equivalent to those in the supernatant could not reconstitute the response caused by the supernatant. T8+ cells activated by supernatants obtained from PWM-pulsed T4+ cells suppressed fresh PWM cultures. Although exhibiting little proliferation, T8+ cells cultured for 6 d in PWM plus IL-2 still suppressed a fresh PWM response. The supernatants therefore contain an additional T suppressor cell growth factor (TsGF). Elaboration of TsGF required radiosensitive T4+Leu8+ cells. Molecular weight determination by high performance liquid chromatography gave a single peak of TsGF activity at approximately 8,000. Finally, whereas TsGF in the absence of IL-2 could not support the proliferation of T suppressor cells, it did cause T8+ cells to become strongly IL-2 receptor-positive.
D000911:Antibodies, Monoclonal / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis; D002455:Cell Division / Q000187:drug effects; D006133:Growth Substances / Q000096:biosynthesis*; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D006801:Humans; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000302:isolation & purification; D007375:Interleukin-1 / Q000302:isolation & purification; D007376:Interleukin-2 / Q000302:isolation & purification; D008970:Molecular Weight; D011043:Pokeweed Mitogens / Q000494:pharmacology*; D006377:T-Lymphocytes, Helper-Inducer / Q000166:cytology*; D050378:T-Lymphocytes, Regulatory / Q000166:cytology*
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D006133:Growth Substances; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II; D007375:Interleukin-1; D007376:Interleukin-2; D011043:Pokeweed Mitogens; D007371:Interferon-gamma