Acid mucopolysaccharide metabolism in leprosy. 2. Subcellular localization of hyaluronic acid and beta-glucuronidase in leprous infiltrates suggestive of a host-Mycobacterium leprae metabolic relationship.

Electron- and light microscopic analyses were conducted on leprosy skin biopsies relative to the origin of hyaluronic acid, which has previously been observed to be distributed inversely in ratio to the degree of cell- mediated immunity. The present study investigated the subcellular localization of hyaluronic acid and its degrading enzyme in various types of leprosy. Hyaluronic acid in some lepromatous leprosy cases was shown to be accumulated in the limiting membranes of the phagosomes of lepra cells and Myco-bacteria leprae have beta-glucuronidase which plays a role in the degradation of hyaluronic acid. Contrariwise, in tuberculoid leprosy, beta-glucuronidase was detected in the lysosomes of epithelioid cells and giant cells. This result suggests that the origin of hyaluronic acid is in histiocytes and at the same time it might suggest that M. leprae is in competition with enzymes of epithelioid cells for hyaluronic acid, whereas reduced or absent beta-glucuronidase in lepra cells enable bacilli to utilize the AMPS as a nutrient.