Autoantibodies in lepromatous leprosy.

Lepromatous leprosy patients often develop erythema nodusum leprosum (ENL) reactions mainly during treatment of the disease. Hence, this study sought to investigate correlation between the prevalence of certain autoantibodies and ENL reactions in these patients. The patients included in the study were fifty patients with lepromatous leprosy and a similar number of normal controls. Sera were collected from the patients and normal controls and the prevalence of circulating rheumatoid factor antinuclear and antismooth muscle antibodies was determined. The prevalence of autoantibodies was increased in lepromatous leprosy as compared with normal controls. The prevalence of these autoantibodies were affected differently by the ENL reactions. ENL lepromatous leprosy showed a slight decrease in prevalence of antinuclear and antismooth muscle antibodies, whereas there was a slight increase in the prevalence of rheumatoid factor in ENL lepromatous leprosy. The levels of serum immunoglobulins tended to show a decline towards ENL lepromatous patients compared with the uncomplicated lepromatous patients. The significance of these finding is discussed in relation to their possible role in the pathogenesis of ENL reaction. It is concluded that some of these autoantibodies and immunoglobulins may be utilized during ENL reactions in the formation of immune complexes.