A T lymphocyte subpopulation in multiple sclerosis patients bearing Fc receptors for both IgG and IgM1.

Abnormally low proportions of total T lymphocytes were found in peripheral blood lymphocytes (PBL) of patients with multiple sclerosis (MS) accompanied by high proportions of T lymphocytes with Fc receptors (FcR) for IgG (T gamma cells). Seventy-five percent of the MS patients had greater than 40% T gamma in the T lymphocyte-enriched population. In 6 out of 16 cases, T mu were also elevated. This elevation, however, did not seem to correlated with disease stage. By mixed rosetting and direct observation with an indirect immunofluorescence test, 30 to 50% of the T gamma cells in MS PBL were also shown to bear FcR for IgM. This population bearing FcR for IgG and IgM, designated T gamma mu, was usually found to be 10% or less of the T gamma population in normal controls. The significance of this T gamma mu population for the MS disease process requires further evaluation.