Comparison between anti-PGL-I serology and Mitsuda reaction: clinical reading, microscopic findings and immunohistochemical analysis.

The lepromin test, serum IgM antibodies against Mycobacterium leprae and in situ observations of T cell subsets in biopsies of Mitsuda reaction using monoclonal antibodies were performed on 44 untreated leprosy patients belonging to various classifications of the disease. The Mitsuda reaction was accessed clinically and histologically after 28 days. Clinical reading and histological analysis of Mitsuda reaction showed good agreement. The high positivity in clinical reading correlated with compact granulomas in histology. There is a graduation of Mitsuda reaction that follows the immunological spectrum of the disease. The histological study of Mitsuda reaction is valuable to confirm the immunological condition in doubtful clinical reaction. Anti-PGL-I IgM levels correlated with disease classification, increasing from the tuberculoid towards the lepromatous pole of the disease spectrum. There was an inverse correlation between serum IgM antibody levels and clinical and histological reading of Mitsuda reaction. There were no statistical difference in quantities and distribution of CD4+ and CD8+ T cells in all Mitsuda reactions. The pattern of cellular content of Mitsuda reaction could not be related to the T cells.