Mycobacterium leprae specific antibodies detected by radioimmunoassay.

A radioimmunoassay was developed for demonstration of antibodies against M. leprae specific antigenic determinants. The specificity of the assay was tested with hyperimmune rabbit antisera against other mycobacteria and shown to be very high. The titre of M. leprae specific antibodies in a lepromatous serum pool was 10(5). Sixty-one of sixty-two lepromatous sera, all of twelve borderline sera and twenty of forty-eight tuberculoid sera were positive in the assay, whereas all of thirty-eight control sera from tuberculin positive individuals from a leprosy non-endemic area were negative. Aplication as a diagnostic test for subclinical infection with M. leprae is discussed. The principle of the test appears promising for serological distinction between pulmonary infection with M. tuberculosis and other mycobacteria.