Reduced in vitro tuberculin reactivity of lymphocytes from patients with tuberculosis

29 patients with newly diagnosed tuberculosis, and matched healthy controls, were studied on the basis of 3H-thymidine incorporation of peripheral blood mononuclear cells (PBMC) induced in vitro by staphylococcal enterotoxin A plus tetrahydrophorbyl acetate (SEA+TPA) or tuberculin purified protein derivative (PPD). PBMC from patients had normal SEA+TPA-induced, but depressed spontaneous (p less than 0.01) and PPD-induced (p less than 0.01) 3H-thymidine uptake. Their peak responses tended to occur later (p = 0.007) and with larger doses of the antigen (p = 0.02). The group of patients with low in vitro PBMC responses to PPD were not clinically distinguishable with respect to the extent of pulmonary tuberculosis, cutaneous reactivity to PPD, nutritional status, bacillary content of sputum or time to sputum sterilization during treatment. Evidence for a plasma factor blocking lymphocyte proliferation was not found in 15 patients tested. Chemotherapy was associated with restoration of normal PPD-induced 3H-thymidine uptake, concomitant with clinical improvement and recovery of nutritional abnormalities.