The E-rosette test: variations in results using E from different sheep. Effect of FCS and of AET treatment.

Sheep erythrocyte (E) rosette tests were performed with E from 3 different sheep. The E rosette test for "active" T lymphocytes was performed with untreated E. E tests for the quantitation of the total number of T lymphocytes were performed with untreated as well as AET-treated E, in assays with and without fetal calf serum (FCS). Lymphocytes from patients with active and stable multiple sclerosis (MS) and with infectious mononucleosis (IM) as well as from healthy individuals were examined. The "total" E test performed with untreated E from one sheep and lymphocytes from patients with active MS gave lower percentages of rosette-forming cells (RFC) than when E from the other two sheep were used. FCS in the medium, or AET treatment of E partly but not wholly abrogated this difference. The origin of the E is thus of importance for the results of the rosette tests in patients with active MS, even if FCS or AET treatment is used.