Cell-mediated immune responses in sarcoidosis.

In an attempt to understand divergent observations regarding the in vitro lymphocyte responsiveness to antigens and mitogens, the frequency of cutaneous reactivity, and the relationship of these variables to clinical features of sarcoidosis, we examined cell-mediated immune responses in 75 untreated patients. In vitro lymphocyte responses to phytohemagglutinin and concanavalin A were significantly decreased among the group of patients with chronic active disease. In vitro lymphocyte responses to streptococcal antigen paralleled the patient's cutaneous reactivity; however, when compared to healthy persons, patients with sarcoidosis responded significantly less often to streptococcal skin tests. Twelve of 13 persons expected to be tuberculin positive by clinical history were found to be dermally reactive, and 11 these 12 exhibited positive in vitro lymphocyte responses to purified protein derivative. Among the remaining 62 patients, failure to respond to all stimuli in vivo and in vitro occurred in only 10. No evidence was found to support the general view that sarcoidosis is characterized by anergy to specific antigens. The patterns of responses to mitogens were neither characteristic nor unique for sarcoidosis. In patients in whom diminished specific cellular immune reactivity was observed, no correlation was evident with specific clinical features of the disease.