CELLULAR REACTION TO MYCOBACTERIUM-AVIUM COMPLEX (MAC) CLINICAL ISOLATES DIFFERING IN HEMOLYTIC-ACTIVITY AND VIRULENCE FOR C57BL 6 MICE/

In this study we showed that Mycobacterium avium complex (MAC) clinica l isolates differed by the expression of hemolytic activity. Two hemol ytic MAC strains were less susceptible to the mycobactericidal effect of murine macrophages than two unhemolytic MAC isolates. In vivo, hemo lytic MAC bacilli survived in the spleens of infected mice for a longe r time than unhemolytic MAC strains. This suggested a role of hemolysi ns in the virulence of MAC strains. There was no difference in the cyt otoxicity of T cells from mice immunized with M. bovis BCG towards mac rophages infected in vitro with MAC strains expressing or not expressi ng hemolytic activity.