INHIBITION OF COMPLEMENT ACTIVITY IN MURINE LEPROSY

NIH mice infected with Mycobacterium lepraemurium (MLM) show a marked depression in their levels of hemolytic complement that is proportiona l to the degree of infection. The defect affects more the activation o f complement through the classical pathway (CPW) than the activation o f complement through the alternative pathway. Although this low activi ty of CPW-complement may be due to different causes (complement consum ption by the infecting microorganism, lack of biosynthesis of compleme nt components, or the presence of complement inhibitory factors), our results seem to support the last possibility. The generation of factor s in the infected animals that inhibit the autologous activity of comp lement as the infection goes on reduces the risk of complement-mediate d tissue damage and prolongs the survival time of the host, a wise str ategy on the part of the MLM to assure its own survival as a parasite.