HLA antigens and neural reversal reactions in Ethiopian borderline tuberculoid leprosy patients.

Reversal reactions (RR) or acute neuritis episodes are frequently observed in borderline tuberculoid (BT) leprosy patients during the first year of treatment, and are associated with a rapid increase in cell-mediated immunity. Because HLA-linked genes have been shown to be an important factor in determining the type of leprosy that develops in susceptible individuals and because HLA molecules regulate cellular interactions in the immune system, we have investigated whether RR are associated with HLA antigens in Ethiopian patients. The data reported here indicate that this is not the case: no significant differences in the distribution of HLA class I and class II antigens were observed among three groups: 28 BT patients with a history of RR, 27 BT patients with no history of RR, and 33 healthy individuals. In contrast to these negative results, we observed that HLA-DR3 was associated with high skin-test responsiveness against Mycobacterium leprae antigens among RR patients. Since DR3 was not associated with RR per se, the observed DR3-associated high responsiveness to M. leprae may not be primarily related to the development of RR.