Thalidomide induces imbalances in T-lymphocyte sub-populations in the circulating blood of healthy males.

Lepromatous leprosy patients experiencing erythema nodosum lepro­ sum (ENL) have been reported to have an increase in the ratio of circulating T -helper to T -suppressor cel ls ( H : S ratio) . Thal idomide is an effect ive drug in the management of ENL . To determine if thal idomide affected cells of the immunoregulatory system, B cel ls , T cel ls , T-suppressor cel ls , T-helper and natural k il ler cel ls i n the blood of the healthy males were enumerated . Thalidomide induced a decrease in the T-helper to T-suppressor cel l rat io . The decrease was due to a significant reduction in the percentage and absol ute number of T-helper cells and an apparent increase in the percentage and absolute number of T-suppressor cel ls . B cel ls and natural k i l ler cells were not affected . Thalidomide's abi l ity to decrease the H : S ratio in healthy individuals suggests that i t may act in ENL by reducing an elevation of that ratio.