Heterogeneity of serological responses in paucibacillary leprosy--differential responses to protein and carbohydrate antigens and correlation with clinical parameters.

We have examined the serological responses of 154 untreated paucibacillary (PB) leprosy patients to two carbohydrate and one protein antigens of Mycobacterium leprae. There was a heterogeneous response with 20% of PB patients having IgM anti-PGL-I antibodies and a similar proportion with IgG anti-LAM antibodies, while 33% had antibodies to the M. leprae-specific epitope on the 35-kDa protein. There was overlap in the responses such that 43% of the patients were seropositive in one of the two M. leprae-specific assays, while 49% were positive in any assay. There was a gradation in seropositivity with increasing extent of disease for each of the clinical parameters measured. Those with established disability at the time of presentation were more likely to be seropositive in each assay.