Recombinant human interleukin-2 reverses in vitro-deficient cell-mediated immune responses to tuberculin purified protein derivative by lymphocytes of tuberculous patients.

In vitro lymphocyte proliferative response to purified protein derivative of tuberculin (PPD) was investigated in patients with tuberculosis. Peripheral blood lymphocytes (PBL) from patients with advanced, refractory tuberculosis showed a significantly depressed response compared with the response of PBL from patients with newly diagnosed tuberculosis (P less than 0.01). A further characterization of this low responsiveness to PPD revealed that PBL from these advanced tuberculous patients failed to generate interleukin-2 (IL-2) in response to PPD stimulation. IL-2 receptor (Tac antigen) expression on the surface of T cells after PPD stimulation was also impaired, although to a lesser extent, in the patients with advanced, refractory tuberculosis. We attempted to overcome the depressed in vitro response observed in PBL from patients with advanced, refractory tuberculosis and found that the addition of exogenous, recombinant IL-2 returned the depressed PPD-induced PBL proliferation in these patients to the level of response observed in PBL from patients with newly diagnosed tuberculosis. The addition of recombinant IL-2 also had a restorative effect (up regulation) in vitro on the partly impaired PPD-induced IL-2 receptor expression by PBL from the patients with advanced, refractory tuberculosis. Our results suggest that recombinant IL-2 may offer a novel approach to the therapy of advanced, drug-resistant tuberculosis.