Interaction of immune complexes and T suppressor cells in sarcoidosis.

Circulating immune complexes were present in half of 31 patients with sarcoidosis and raised levels were associated with low numbers of T suppressor cells (T gamma- and Fc gamma-receptor-positive lymphocytes). Incubation of T cells with trypsin restored the percentage of T gamma cells to within or above the normal range. Incubation of normal lymphocytes with sarcoid immune complexes significantly reduced the number of detectable T gamma cells. Preincubation of normal lymphocytes with circulating immune complexes significantly reduced their blastogenic response to concanavalin A. These studies suggest an interaction between immune complexes and T suppressor cells in sarcoidosis and emphasise the importance of immune complexes in modulating the immune response.