Up-and Down-Regulation of Lymphocyte Proliferation and PFC Response by Mast Cells

Abstract

Mast cells induced from normal mouse spleen cells by long-term culture showed strong regulatory effects on lymphocytes. These cells affected the kinetics ofin vitroplaque-forming cell (PFC) responses to sheep red blood cells (SRBC) . PFC responses were enhanced in an early phase (2^ndand 3^rdday), but suppressed in a later phase (4^thand 5^thday) . Thymocyte response to Con A, and B cell response to LPS were suppressed by mast cells. Supernatant collected from cultured mast cells enhanced PFC response and thymocyte response to Con A, but B cell response to LPS was suppressed. After Con A stimulation, the mast cell supernatant suppressed the B cell response more strongly. The thymocyte response to Con A was also suppressed. Large doses of the Con A-stimulated mast cell supernatant partially suppressed the PFC response. Up- and down-regulatory factors in the conditioned mast cell supernatant were responsible for the immunoregulatory functions of the mast cells, which was confirmed by chromatography and SDS-PAGE analysis. Further experiments are needed to identify these up- and down-regulatory factors.