Decrease of three lysosomal enzymes in guinea pig macrophages activated by lymphocyte mediators.

Guinea pig peritoneal macrophages incubated for 72 h with MIF-rich medium which results in an activation of certain physiological functions have decreased specific activity of the lysosomal enzymes, acid phosphatase,Β-glucuronidase, and cathepsin D, and decreased phagocytosis of denatured particulate hemoglobin in comparison to control cells. Enhanced release of enzymes does not account for the decrease in lysosomal enzyme activity because these enzymes cannot be detected in the supernatant of the cells. Furthermore, when macrophages are activated by whole sensitized and stimulated lymphocytes, the specific activities of the lysosomal enzymes are also decreased or unchanged. It is therefore unlikely that the defense mechanisms of macrophages which are enhanced by lymphocyte mediators include an increase in lysosomal enzyme activity.