A follow up of T-cell subsets and of anti-M. leprae antibody titer as measured by the FLA-ABS test in Melanesian leprosy patients under polychemotherapy.

Melanesian leprosy patients from New Caledonia were studied for the following parameters during the course of polychemotherapy: peripheral blood T-cell subsets, as identified in an immunofluorescence assay with monoclonal antibodies OKT3 ("pan-T"), OKT4 ("helper/inducer"), and OKT8 ("cytotoxic-suppressor"), and anti-Mycobacterium leprae antibodies in the serum, as measured by the fluorescent leprosy antibody absorption test. A group of Melanesian healthy subjects with no known exposure to M. leprae served as controls. Healthy contacts of leprosy patients were also studied for the presence of anti-M. leprae antibodies. Untreated, nonreactional lepromatous patients displayed moderate but significant T-cell abnormalities, consisting of a decrease in the percentage of OKT3+ and OKT4+ cells with a decrease in the OKT4:OKT8 ratio. These abnormalities disappeared within nine months of treatment. A transient decrease in the percentage of OKT8+ cells with an increase in the OKT4:OKT8 ratio was seen in patients suffering erythema nodosum leprosum (ENL). Tuberculoid patients, whether treated or not, did not show any T-cell marker disturbances. Positive serological tests for anti-M. leprae antibodies were found in 100% of lepromatous patients, 92% of tuberculoid patients, and 56% of healthy contacts. No significant decline in the antibody titer was observed with treatment during the survey period.