Inhibition of polyclonal B-cell activation by suppressor monocytes in patients with sarcoidosis

The present study employed a direct plaque-forming cell (PGC) assay following pokeweed mitogen (PWM) induced polyclonal activation of B lymphocytes in sarcoidosis to evaluate the in vitro humoral immune response in this disease and to delineate the immunoregulation of this response. Sarcoidosis lymphocytes had a suppressed PFC response to polyclonal activation, but were unable to suppress normal B-cell PFC responses in allogeneic co-cultures. Removal of a cell type, which was corticosteroid-resistant, radio-resistant, adherent and a non-T cell, from sarcoidosis mononuclear cell suspensions reversed the suppressed PFC response, indicating the presence of a suppressor monocyte. Thus in vitro suppressor cell activity has now been demonstrated in this disease, which is characterized by multiple immunological aberrancies.