Activated T lymphocytes in patients with multiple sclerosis.

We used four monoclonal antibodies designated MLR-1, -2, -3, and -4, specifically directed against determinants uniquely present on activated T lymphocytes to analyze peripheral blood lymphocytes (PBL) of patients with multiple sclerosis (MS). By indirect immunofluorescence techniques, we found that many PBL expressed one or more of these activation antigens. Thus, high percentages of MLR-2 positive cells were found in all 20 MS patients (66 +/- 12% in 13 patients with the remitting form and 57 +/- 14% in 7 patients with the progressive form). MLR-3 positive cells were found in three patients with the remitting form and five patients with progressive MS, MLR-4 in seven patients with remitting MS and in five with the progressive type. MLR-1 positive cells were prominent in only two cases (one remitting and one progressive). Discrepancies between expression of MLR antigens and molecules coded by the HLA-DR region (Ia antigens) were observed.