Relationship between CD5+ B lymphocytes and the activity of systemic autoimmunity.

We studied the relationship between CD5+ B cells and the activity of the disease process in patients with autoimmune diseases. In rheumatoid arthritis (RA), levels of CD5+ B cells were associated with autoantibody production as determined by serum rheumatoid factor and antinuclear antibodies. In addition, CD5+ B cells were significantly correlated with C-reactive protein, and data from longitudinal studies showed a marked influence of corticosteroid treatment on numbers of CD5+ B cells. Patients with systemic lupus erythematosus (SLE) had slightly elevated levels of CD5+ B cells as compared with normals, but a close association with measures of an active disease was not observed. In a group of patients with type I diabetes mellitus, CD5+ B cells were detected in patients with anti-islet cell antibodies. Our results suggest that CD5+ B cells are related to the activity of the autoimmune process and can be modulated by therapy in patients with RA. Although CD5+ B cells do not seem to have a major role in SLE, polyclonal activation might affect this B cell subset as well in this disease. Further studies are needed to define the precise role of CD5+ B cells in organ-specific autoimmunity.