Description:
<jats:title>Abstract</jats:title><jats:p>The presence of clonally restricted B lymphocytes in the peripheral blood of patients with multiple sclerosis (MS) was investigated using a cytofluorometric technique able to detect lymphocytes having homogeneous amounts of surface immunoglobulin of one light chain class. Thirty‐five of 76 analyses (46%) performed on 63 MS patients were positive for increased numbers of clonally restricted B cells as compared with only 7 of 27 (26%) in patients with other neurological diseases (<jats:italic>p</jats:italic> < 0.05) and 9 of 36 (25%) in control subjects (<jats:italic>p</jats:italic> < 0.05). This B cell population expressed predominantly kappa light chain determinants in 16 of 18 MS patients (89%) but in only 6 of 11 (55%) controls (<jats:italic>p</jats:italic> < 0.005). There was no correlation between the presence of abnormal B cell clones in peripheral blood and either disease activity or serum antimeasles antibody titers. The results demonstrate that there are increased numbers of clonally restricted B cells in the peripheral blood of MS patients which may be related to the oligoclonal immunoglobulin found in the serum and cerebrospinal fluid.</jats:p>