The in vitro effect of thymic humoral factor and levamisole on peripheral blood lymphocytes in systemic lupus erythematosus patients.

The in vitro effect of thymic humoral factor (THF) and levamisole on E rosette-forming cells in the peripheral blood of seventeen patients with systemic lupus erythematosus (SLE) was studied. Patients with active disease showed a low number of E rosette-forming cells. A significant rise in the number of E rosettes was obtained after incubation with both THF and levamisole. No such effect was observed on lymphocytes from patients with inactive disease and normal controls. In seven patients, three with active disease and four with well-controlled disease, short-term cultures were performed. The effect of THF on E rosettes was found to be the same before and after the short-term cultures. Possible mechanisms, by which THF (on the one hand) and levamisole (on the other) may increase the number of E rosettes in vitro, are discussed.