Immune responses to recombinant proteins of Mycobacterium leprae

Identification of antigenic determinants of the polar immune response in leprosy may illuminate both protection and pathogenesis. Thirty subjects were studied (22 with polar disease and 8 healthy controls who were heavily exposed but disease-free) by assaying the proliferative, interferon (IFN)-gamma, and antibody responses to recombinant antigens of Mycobacterium leprae (10, 28, 36, and 65 kDa). The 10-kDa antigen elicited IFN-gamma production from all tuberculoid (TT) and borderline tuberculoid (BT) patients but little from controls, lepromatous (LL), or borderline lepromatous (BL) patients (P<.05). Production of 65-kDa-specific IFN-gamma was higher in TT/BT than in controls or LL/BL patients (P<.006). All subjects produced 65-kDa-specific antibody, but it was higher in LL/BL patients than in healthy controls, whose responses were higher than in TT/BT subjects (P=.035). The 36-kDa antibody responses were selectively increased in LL/BL subjects (P<.02). The intermediate phenotype of the controls suggests that M. leprae-specific production of IFN-gamma may contribute to pathology and to protection in leprosy.