Defective cell mediated immunity in sarcoidosis: effect of interleukin-2

Interleukin-2 has been reported to enhance the immune response in diseases characterised by defective cell mediated immunity. The effect of exogenous recombinant interleukin-2 was studied on the proliferative and cytotoxic responses of peripheral blood mononuclear cells from 39 patients with sarcoidosis and 14 healthy control subjects. The proliferative response to purified protein derivative was smaller in patients than in control subjects (p less than 0.001) whereas the response to 80 U interleukin-2 alone and to purified protein derivative and interleukin-2 did not differ significantly between the two groups. In addition, in eight patients but no control subjects tritiated thymidine incorporation induced by the combination of purified protein derivative and interleukin-2 was more than twice the sum of that induced by purified protein derivative and interleukin separately. Cytotoxic activity occurring spontaneously and induced by purified protein derivative and interleukin-2 in blood mononuclear cells was significantly less for patients with sarcoidosis than for control subjects (p less than 0.05 spontaneous, less than 0.001 purified protein derivative induced, less than 0.02 interleukin induced). Synergism between antigen and interleukin did not occur with respect to the cytotoxic response in either patients or controls. Defective interleukin-2 production may contribute to, but does not entirely explain, the functional abnormalities of peripheral blood lymphocytes from patients with sarcoidosis.