Thalidomide does not modify the ability of cells in leprosy patients to incorporate [3H]-thymidine when incubated with M. leprae antigens.

The immune response in reversal reaction, (RR) and in erythema nodosum leprosum (ENL) is characterized in vitro by an enhancement in lymphocyte blast transformation against M. leprae. As thalidomide is an effective treatment for ENL, this study assessed the effect of this drug on these phenomena. Mononuclear cells from patients attending the clinic at ALERT and from healthy staff were cultured for 5 days with integral M. leprae (IMl), or a modified Dharmendra antigen (Dhar), or PPD from M. tuberculosis. In one set of cultures, thalidomide was added once at the initiation of the culture; in the other set thalidomide was added a second time (2x), 18 h prior to harvesting the cells. The mononuclear cells, in the absence of thalidomide, from healthy staff, borderline tuberculoid patients (BT) and BT patients in RR (BT/RR) incorporated [3H]-thymidine best when cultured with PPD > Dhar > M. leprae. The cells from patients with ENL did not respond well to the M. leprae antigens. Thalidomide (2x) enhanced proliferation to Dhar in the BTRR group (Wilcoxon signed rank test, P < 0.05). No significant changes occurred for the other groups. Comparing PPD-stimulated cells treated with thalidomide once to those treated with thalidomide twice, thalidomide (2x) suppressed incorporation of [H3]-thymidine by the PPD-stimulated (P < 0.05) as well as IMl-stimulated (P < 0.05) cells in the healthy staff group. In the Dhar-stimulated cells from the healthy staff thalidomide significantly suppressed TNF-alpha (P < 0.05). A mixed effect was seen within and between the other groups, but there was a trend for thalidomide to suppress TNF-alpha induced by the M. leprae, Dhar and PPD antigens.