Lymphocyte subsets, phytohaemagglutinin responsiveness of blood lymphocytes, and interleukin 2 production in sarcoidosis.

To test the possibility that T lymphocyte subset imbalance and interleukin 2 (IL2) play a part in the impairment of cellular immune response in sarcoidosis, the proportion of T lymphocyte subsets in peripheral blood and alveolar lavage fluid from 21 patients with sarcoidosis was studied, monoclonal antibodies OKT3, OKT4, and OKT8 being used. Lectin induced production of IL2 and phytohaemagglutinin (PHA) responsiveness of peripheral blood lymphocytes were investigated. The percentage of both OKT3+ and OKT4+ T lymphocytes was significantly lower in peripheral blood from patients with sarcoidosis than in control subjects (control 63% and 46%), more so in patients with chronic sarcoidosis (44% and 23%) than in patients with recent sarcoidosis (56% and 38%). PHA induced IL2 production from peripheral blood lymphocytes did not differ between patients with sarcoidosis and control subjects. There was a significant positive correlation between PHA responsiveness and the percentage of blood OKT3+ and OKT4+ cells. Peripheral blood lymphocyte PHA responsiveness was decreased only in patients with an OKT4/OKT8 ratio of less than 1.5. Finally, late addition of exogenous IL2 to the culture medium on day 5 increased 3(H)Tdr incorporation by PHA stimulated blasts in peripheral blood lymphocytes from normal subjects, but not from those of patients with sarcoidosis. The data suggest that the impairment of cellular immune response in patients with sarcoidosis could in part reflect a decrease in the percentage of blood T helper lymphocytes and impaired IL2 receptors at the surface of stimulated lymphocytes.