Experimental murine leprosy: a biochemical study emphasizing lysosomal enzyme changes in vivo and enzyme secretion by macrophages in vitro.

This study was undertaken to identify biochemical alterations in serum, lymphoid organs, and peritoneal macrophages (PM) which reflect the histopathology of experimental Mycobacterium lepraemurium (MLM) infection in mice. A significant increase of acid phosphatase, beta-glucuronidase, N-acetyl-beta-D-glucosaminidase, and lysozyme was found in serum, spleen, and liver homogenates of mice infected intraperitoneally (ip) with MLM. PM from infected mice showed a substantially greater rate of secretion of beta-glucuronidase, N-acetyl-beta-D-glucosaminidase, and acid phosphatase than PM from normal mice. There was, however, no significant difference in the ability of PM from BALB/c and C57BL/6 mice to secrete such enzymes in vitro. There was also a significant increase in all these enzymes in PM in the early stage of infection but they dropped to values lower than normal in the advanced stage of infection despite the fact that such cells increased in size and protein content as the infection progressed. Infected mice were also found to have progressively elevated levels of serum lactic dehydrogenase, glutamic oxaloacetic, and glutamic pyruvic transaminases which indicated damages of hepatocytes and other tissues. Values of other blood components were also reported. Both BALB/c and C57BL/6 strain of mice, which are susceptible to the ip route of MLM infection, showed an indistinguishable pattern of biochemical alterations as reflected by their similar histopathological changes in various organs. BALB/c mice, which are still susceptible to subcutaneous (sc) route of infection showed similar characteristic changes in various serum components as before. In contrast, C57BL/6 mice, which are resistant to MLM infection sc, showed insignificant alterations in most of these biochemical parameters.