ANALYSIS OF CIRCULATING IMMUNE-COMPLEXES FROM LEPROSY PATIENTS FOR MYCOBACTERIUM-LEPRAE ANTIGENS

There is considerable evidence implicating immune complexes (ICs) in an array of pathogenic and immunomodulatory mechanisms in a variety of diseases (28). In leprosy also, ICs have been demonstrated along the clinico-immunopathological spectrum of the disease (1, 16,19,21). Apart from being held responsible for the pathogenesis of reactions-the acute inflammatory episodes often seen after the initiation of antileprosy chemotherapy (19, 27) - these ICs are suspected of playing a large immunomodulatory role in leprosy. Antigens of Mycobacterium leprae (and corresponding antibodies) are regarded as the obvious constituents of ICs in leprosy patients (4, 16). Thus, the analysis of these complexes is expected to throw light on the identities of immunopathologically important antigens of M. leprae which have largely remained elusive (9). The present study, aiming at the demonstration and characterization of M. leprae antigens in circulating ICs (CICs), was conducted in leprosy patients suffering from the disease at both ends of the leprosy spectrum, i.e., tuberculoid and lepromatous (21). In addition to two polyclonal antibodies, pooled lepromatous (LL) serum and anti-BCG antibody, a set of presently available monoclonal antibodies against M. leprae (10, 11) was also used for this purpose. Sera were investigated individually, and a correlation of the results was sought with the clinico-bacteriological status and circulating M. leprae-specific antibody levels (5, 22) of the patients.