Macrophage membrane alterations in leprosy as determined by change in sialic acid level.

The level of sialic acid removable by neuraminidase from macrophages of bacteriologically-positive lepromatous leprosy (B(+)LL) patient is extremely low, compared to macrophages from tuberculoid leprosy patients or normal individuals. On the other hand macrophages from long term treated bacteriologically-negative lepromatous leprosy (B(-)LL) patients show a much higher level of sialic acid. This higher level is drastically reduced when these macrophages from (B(-)LL) patients are allowed to phagocytose Mycobacterium leprae. This modulation could be host- and pathogen-specific. It is demonstrated that M. leprae infection brings out membrane changes in the macrophages leading to alteration in the surface molecules. Such membrane changes may cause hindrance in the ability of macrophages to participate successfully in the immune process.