Role of macrophages in defective cell mediated immunity in lepromatous leprosy. II. Macrophage and lymphocyte interaction.

Macrophages from lepromatous patients after phagocytosis of M. leprae showed alteration in their surface property as determined by their ability to express Fc receptors. The same macrophages without intracellular M. leprae show normal Fc receptors. The lepromatous macrophages also show very poor interaction with lymphocytes in the presence of M. leprae while they are able to interact with lymphocytes when exposed to other antigens. These observations along with earlier ones on macrophage defects have indicated a probable reason for defective cell mediated immunity (CMI) in lepromatous leprosy patients. There appears to be a defective macrophage population in lepromatous patients that is unable to process M. leprae antigens and initiate the CMI response.