Serum immune complexes in erythema nodosum leprosum reactions of leprosy.

Serum estimations of immunoglobulins, complement components and their presence in circulating immune complexes were carried out in 39 Lepromatous, 44 ENL and 22 Post ENL leprosy patients. Serum IgG, IgA, IgM, C3 and C4 levels were determined by single radial immunodiffusion. Serum immune complexes were precipitated with Polyethylene Glycol (PEG) and IgG, IgA, IgM, C3 and C4 were estimated by single radial immunodiffusion and expressed as % of precipitation of their serum level. Decreased IgG, IgM; increased IgA and C3; and no change in C4 levels are observed in ENL than Lepromatous and Post ENL patients. However, a gradual insignificant reduction of IgG, IgA, and IgM was found from Lepromatous to ENL and Post ENL patients in the PEG-precipitates. Similarly, C3 and C4 was found reduced insignificantly in ENL than Lepromatous and Post ENL patients. The significance of these estimations in relation to immune status of ENL reactions are discussed.