FC-GAMMA-R-EXPRESSING MONOCYTES ARE NECESSARY FOR PWM-INDUCED PROLIFERATION OF SAIMIRI-SCIUREUS PERIPHERAL-BLOOD MONONUCLEAR-CELLS

When used as a polyclonal activator of blood immunocompetent cells in the squirrel monkey, pokeweed mitogen (PWM) failed to induce lymphopro liferation unless either autologous or human serum was added to the cu lture medium, instead of a serum assumed to be deprived of Ig such as foetal bovine serum. We thus attempted to delineate activation process es initiated by PWM and which required both monocytes and native Ig mo lecules. For instance, the physical presence of live monocytes within lymphocyte suspensions vs. paraformaldehyde-fixed monocytes or product s of monocytic origin was an absolute prerequisite for inducing squirr el monkey lymphocytes to proliferate in the presence of PWM. In additi on, a combination of monocytes and native Ig were further shown to ind uce lymphocytes to proliferate in the presence of PWM. We therefore qu estioned whether FcgammaR on the surface of monocytes vs. FcgammaR exp ressed by other cells were involved in the initiation of PWM-driven ly mphoproliferation. PWM may represent a useful tool for studies of Fcga mmaR-mediated immunological processes.