Coordinate expansion of 'fetal type' lymphocytes (TCR gamma delta+T and CD5+B) in rheumatoid arthritis and primary Sjögren's syndrome.

In the blood of 10 patients with rheumatoid arthritis (RA), the number of TCR gamma delta+T cells and CD5+B cells was 5.5% +/- 4.38 and 34.3% +/- 20.62 (mean +/- s.d.), respectively. In 12 patients with primary Sjögren's syndrome (SS) the mean +/- s.d. of these T and B cell subpopulations was 4.75% +/- 3.85 and 38.75% +/- 22.68. These values were significantly increased as compared with the circulating T and B cells from 22 healthy subjects in whom TCR gamma delta+T cells were 2.09 +/- 1.01 (P less than 0.001 for RA; P less than 0.004 for SS) and CD5+B cells were 18.09% +/- 4.47 (P less than 0.001 for RA and SS). This increase was not influenced by disease activity. Furthermore, there was a marked correlation (P less than 0.001) between the levels of TCR gamma delta +T cells and CD5+B cells. This novel finding of coordinate elevated levels of lymphocytes with fetal phenotypes in RA and primary SS suggests an immunological imbalance that may have implications in these diseases.