IgA and IgM antibodies against Mycobacterium leprae in cord sera and in patients with leprosy: an indicator of intrauterine infection in leprosy.

A solid-phase radioimmunoassay was developed for demonstration and quantification of IgA and IgM anti-M. leprae antibodies. IgA and IgM anti-M. leprae antibodies were demonstrated in a lepromatous serum pool, in various amounts in individual patients with lepromatous leprosy, and in lower concentration in tuberculoid leprosy and non-leprosy controls. IgA and IgM anti-M. leprae antibodies were demonstrated in cord sera from babies of mothers with leprosy. The reliability of fetal IgA and IgM antibody synthesis as an indicator of intrauterine infection in leprosy is discussed.