Elevated soluble CD23 levels in the sera from patients with localized scleroderma

Soluble CD23 (sCD23) is closely related to B-cell activation and elevated serum levels of sCD23 have been reported in several autoimmune disorders. This study investigated the serum levels of sCD23 and determined the correlation of sCD23 with other immunologic abnormalities and clinical features in localized scleroderma. We examined 49 serum samples by an enzyme-linked immunosorbent assay in the following three subgroups: 15 patients with generalized morphoea, 22 with linear scleroderma, and 12 with morphoea. The serum levels of sCD23 were significantly elevated in patients with localized scleroderma, compared with those in healthy individuals. Of the three subgroups of localized scleroderma, patients with generalized morphoea had the highest levels of serum sCD23. The frequency of IgM antihistone antibody (AHA) and IgM rheumatoid factor (RF), the number of linear lesions, and the frequency of muscle involvement were significantly higher in patients with elevated sCD23 levels than in those with normal levels of sCD23. A significant correlation between the serum sCD23 level and the number of involved areas of the body was observed. Our data suggest that the activation of virgin B cells, which is reflected by elevated sCD23 levels, is closely associated with the production of IgM autoantibodies in localized scleroderma and furthermore that the serum levels of sCD23 are a new serological indicator of the severity of localized scleroderma.