Imbalances in T cell subpopulations in lepromatous leprosy.

Circulating T cells, T helper, and T suppressor cells were investigated in 24 lepromatous patients, using murine hybridoma-derived monoclonal antibodies OKT 3, OKT 4, and OKT 8. Six bacillary lepromatous patients without recent eNL were studied; in this group, suppressor cells were increased and helper cells diminished, resulting in a decrease in the helper/suppressor (H/S) ratio. Nine bacteriologically negative lepromatous patients without recent ENL were studied. T cell subsets distribution was normal, although some T cell functions were affected. It was further shown that in non-ENL patients, the diminution of the H/S ratio is correlated with the Bacteriologic Index (BI). Although bacillary, ENL patients exhibit a completely different T cell pattern than non-reactional patients. In these patients, there was a significant diminution of circulating suppressor cells, and an increase in T cell functions. These abnormalities were transient. Our results confirm the importance of suppressor cells in lepromatous leprosy, and suggest that imbalance between helper and suppressor cells may play a role in the pathogenesis of ENL reactions.