Phytohemagglutinin response of lymphocyte fractions isolated by velocity sedimentation and enhanced helper cell activity.

Peripheral blood mononuclear cells from patients with histologically confirmed sarcoidosis were examined for the presence of suppressor activity to explain diminished phytohemagglutinin-induced lymphoblastic transformation. Phytohemagglutinin responses of unfractionated cells, cell fractions obtained by velocity sedimentation, and mixtures of various cell fractions were studied by uptake of thymidine labeled with hydrogen-3 in 72-hour cultures. The in vitro impaired response to phytohemagglutinin stimulation of unfractionated sarcoid lymphocytes occurred only in patients with more disseminated disease (group 2). Sarcoid lymphocyte fractions 2 and 4 showed significantly decreased stimulation with phytohemagglutinin, suggesting that the over-all impaired response of unfractionated sarcoid lymphocytes to phytohemagglutinin stimulation could be explained by the sum of impaired phytohemagglutinin responses of lymphocytes in these fractions. No evidence of suppressor cell activity was detected. In contrast, slowly sedimenting sarcoid fraction 4 cells appeared to have helper activity, and this was independent of the extent of disease and results of skin tests.