A sequential study of circulating immune complexes, complement and immunoglobulins in borderline tuberculoid leprosy patients with and without reactions.

Sequential estimates of the levels of circulating immune complexes (CIC), complement catabolic fragment C3d, complement-mediated immune complex solubilization (CMS) and immunoglobulins were made in 24 newly diagnosed with borderline tuberculoid leprosy over a 20 month period after initiation of chemotherapy. Fourteen of these patients had not suffered from reversal reactions either at the time of presentation or during the follow-up. The levels of CIC were evaluated in them from the third to the eleventh month after starting chemotherapy and immunoglobulin G (IgG) levels were evaluated up to eight months. The concentrations of C3d and immunoglobulins A (IgA) and M (IgM) were normal in these patients. The other ten patients had reversal reaction at the time of diagnosis which subsided by the third month after starting treatment. They did not have reversal reactions later. The levels of CIC and IgG were elevated and those of CMS were depressed throughout the study period. Serum C3d level was initially elevated but came down to normal by the third month while IgA and IgM levels were within normal limits. The relevance of these findings to the genesis of reversal reaction is discussed in this communication.