Isolation and analysis of circulating immune complexes in leprosy.

Circulating immune complexes (CIC) were isolated by two antigen nonspecific methods from 60 leprosy patients belonging to borderline tuberculoid (BT) and lepromatous (LL) types with and without reactions. CIC were elevated in both BT and LL reactions. CIC from BT in reaction (BTR) were found to consist largely of IgG and C3, whereas, C-reactive protein could be found in CIC from LL reactions (LR). In addition, IgM and rheumatoid factor were demonstrated in the complexes of LR patients who had mainly arthritis. Antimycobacterial antibody was seen in the complexes of two-thirds of LR patients who had predominantly skin manifestations as part of their reaction. The relevance of these findings to the clinical manifestations of different types of reactions is discussed.