Use of the anti-PGL-I antibody ELISA and the Mitsuda reaction in early diagnosis of leprosy

ABSTRACT

Cutaneous reaction to the Mitsuda antigen and anti-PGL-I IgM antibodies (ELISA) were determined in 134 leprosy patients, 290 household contacts, 52 healthy controls and 43 tuberculous individuals. The multibacillary patients did nort developed cell-mediated immunity (CMI), although they presented high levels of IgM (absorbance at 492 m > 0.5). The paucibacillatry patients presented CMI, although in varying degrees, and IgM levels did not exceed 0.5 absorbance units. Most of the contacts (107) showed a Mitsuda-postive test, and 25 of then were anti-PGL-I IgM seropositive (absorbance < 0.5 but > 0.22), although none became ill during the twoyear follow-up. Of the 17 Mitsuda-negative contacts, two wxhibited an immunological status of lepromatous leprosy (negative Mitsuda test and positive serology; absorvance > 0.05) and became ill (one borderline lepromatous and one indeterminate leprosy). These results show that the immunological status of lepromatous leprosy can appear prior to clinical symptoms, and thus serology for anti-PGL-I IgM together with the Mitsuda test can be useful in an activbe search for new preclinical cases among high risk populations