The relationship between reactivities to lepromin A (Fernandez and Mitsuda) and a soluble protein antigen of Mycobacterium leprae.

Three methods of evaluation were used to investigate the relationship between skin test reactions elicited by different antigens of Mycobacterium leprae. The latter were the Fernandez and Mitsuda reactions to lepromin, and that to a Soluble Protein Antigen (SPA) of M. leprae. All three methods of evaluation demonstrated some degree of relationship though not as high as would be expected. The closest correlation was between Mitsuda and SPA reactions; while Fernandez and Mitsuda, and Fernandez and SPA reactions showed more or less similar coefficients of correlation.