Phagocytosis in leprosy. 5. The effect of the infection with Mycobacterium lepraemurium on the level of diverse hydrolytic lysosomal enzymes of murine peritoneal macrophages

The effect of the infection with M. lepraemurium on the activity of several lysosomal enzymes of mouse peritoneal cells was studied. The enzymes studied were acid- and alkaline-phosphatases, acid (cathepsin D-type) proteinase, β-glucuronidase, deoxyribonuclease, a nonspecific lipase, and lysozyme. Enzyme determinations were carried out four months and six months after the infection with 15.5 x 10⁷ bacilli per mouse. Clear differences between M. lepraemurium-infected and normal animals were observed at four months of infection, with all of the mentioned enzyme activities well above the normal values. At six months of infection, a tendency to decrease to normal values of the enzyme activities was observed. It is suggested that this biochemical activation of mouse peritoneal cells reflects the effect of the cell-mediated immune response triggered by the infection with the murine leprosy bacillus. M. lepraemurium-infected mice possess macrophages in a high state of biochemical activation; yet, they are unable to get rid of the infecting microorganism.