Leishmania donovani: action of excreted factor on hydrolytic enzyme activity of macrophages from mice with genetically different resistance to infection

The effect of purified excreted factor from promastigotes of Leishmania donovani upon the activity of four enzymes from lysed peritoneal exudate cells of mice (C3H and C57BL) was determined. There was no demonstrable effect on acid phosphatase (EC3.1.3.2), β-glucuronidase (EC3.2.1.21), and N-acetyl-β-glucosaminidase (EC3.2.1.29), but β-galactosidase (EC3.2.1.23) was inhibited up to 72% after 3 hr of incubation at 37 C. Inhibition of C57BL mouse enzymes was not significantly different from that of C3H mice. Protamine sulfate combined with the highly negatively charged excreted factor of L. donovani to migrate as a single positively charged band on immunoelectrophoresis. Protamine sulfate also reversed the β-galactosidase inhibition, though this was without direct effect on the enzyme. The excreted factor did not change or lose its charge or antigenicity with regard to precipitating antibody, when incubated with extracts of mouse peritoneal exudate cells, splenocytes, or liver homogenate—irregardless of whether the mice had been infected with leishmaniasis for 1 or 2 weeks or were uninfected.