Possible role of mast cell membrane structures in the enhancement of spleen cell proliferation

The role of mast cells and their mediators in the regulation of immune processes is an area of current interest. In previous studies, we demonstrated that rat peritoneal mast cells and their supernatants enhance the spontaneous and mitogen-induced proliferation of immunocytes. The results of this paper indicate that the enhancing factor in mast cell supernatants is not dependent on mast cell activation or on the release of mediators from within the mast cell. Instead it seems to be due to the passive diffusion of surface structures during mast cell culture. Pretreatment of mast cells with glutaraldehyde did not alter the ability of intact mast cells to enhance spleen cell proliferation. In contrast, mast cells lost their enhancing ability if they were pretreated with trypsin followed by glutaraldehyde fixation. Based on these data, we suggest that protein membrane structures on the mast cell surface are responsible for a contact cooperation between mast cells and spleen cells and that they cause the enhancing effect on spleen cell proliferation. This type of interaction may be responsible for the regulation of immune cell function during local immune reactions.