CD5+ B lymphocytes and other lymphocyte subsets in primary Sjögren's syndrome.

CD5+ B cells and other lymphocyte subsets were analyzed by flow cytometry in patients with primary Sjögren's syndrome (pSS), in healthy subjects (HS) and in patients with various control diseases. When compared with HS, patients with pSS were found to have similar levels of CD5+ B cells and decreased levels of CD8+ T cells (P = 0.0003). When compared with patients with various other diseases, however, the number of CD5+ B cells in pSS was more than twice as high (P = 0.0002), whereas no difference was found between numbers of CD8+ T cells. When the number of CD5+ B cells was expressed as a percentage of total B cells, the results obtained were similar to those with absolute numbers. Determination of lymphocyte subsets may be used as a diagnostic aid for Sjögren's syndrome in selected patients with suspected immunological diseases of unknown type.