Neutrophilic leukocytes in immunologic reactions in vitro: IV. The effect of trypsin

Prior trypsinization of rabbit PMN prevented the normal selective release of lysosomal constituents induced by contact with zymosan-C3 and abolished the adherence of these cells to sheep RBC sensitized with IgM antibody and complement (PMN rosettes). The effect of trypsin could be completely reversed by exposure of the cells to soybean trypsin inhibitor after trypsinization. Trypsin did not inhibit the lysosomal release provoked by contact with immune complexes of interfere with rosette formation between PMN and sheep RBC sensitized with IgG antibody. The action of trypsin on the PMN C3b receptor may not be enzymatic.