Clinical significance of changes in serum proteins, immunoglobulins, and autoantibodies in leprosy.

Changes in the level of acute phase reactants such as C-reactive protein (CRP), serum globulins, and autoantibodies have been reported previously in patients with leprosy, particularly at the lepromatous end of the spectrum. The clinical significance of these findings was investigated by comparing the same parameters of humoral immune function in populations of Australian Aboriginals with stable treated leprosy and relevant contact groups including a) noninfected European sporadic contacts and b) healthy Aboriginal relatives of patients with confirmed leprosy. Raised levels of CRP and immunoglobulins and the higher frequency of autoantibodies seen in leprosy patients compared with sporadic contacts are probably related to differences in the incidence of nonleprous infection rather than to leprosy per se. Comparable results were obtained in the leprosy patients and their family contacts. The data highlight the need to use antigen-specific assays for determining the significance of changes in acute phase reactants and for distinguishing between the primary and secondary effects of Mycobacterium leprae infection.