Serum immunoglobulins an autoantibodies during and after erythema nodosum leprosum (ENL).

Sera from 20 patients with lepromatous leprosy complicated by erythema nodosum leprosum (ENL) were collected at the time of acute reaction and then after clinical cure four weeks later. Anti-ENL drugs used were: prednisolone (11 patients), chloroquin (6 patients), and clofazimine (3 patients). Immunoglobulins M, G, and A and autoantibodies, namely, antithyroglobulin antibody (ATA), antinuclear antibody (ANA), and rheumatoid factor (RF), were measured in these 20 paired serum samples. The mean serum concentration of IgG showed a significant elevation after clinical subsidence of the reaction, mainly in the prednisolone treated group; while those of IgM and IgA varied only marginally. Autoantibodies were detected in nine patients. Of these, three patients developed these antibodies only after remission of the reaction. Treatment with prednisolone and chloroquin, although causing subsidence of ENL, resulted in an increased incidence of ATA and/or ANA. Furthermore, it was observed that longer duration of illness, higher age group, and history of repeated attacks of ENL predisposed these patients to enhanced autoantibody formation.