The mitogenic and enzymatic activities of polymorphonuclear leukocyte (PMNL) lysosomal proteins examined in vitro.

The lysosomal granules of human and animal PMNL contain the protein factors which stimulate the lymphocyte transformation in vitro. The performed experiments showed that mitogenic activity is not exclusively associated with proteolytic activity. Using column chromatography fractionation, it has been shown that the mitogenic and proteolytic proteins are localized in different fractions. The irreversible inhibition of proteases by di-isopropyl-phosphofluoridate (DFP) increase the mitogenic activity of PMNL lysosomal proteins. The mitogenic proteins are localized in lysosomal granules of secondary density and they are loosely bound to membranes of lysosomal granules.