ANALYSIS OF BCL-2(+) LYMPHOCYTE SUBPOPULATIONS IN INFLAMMATORY SYNOVIAL INFILTRATES BY A DOUBLE IMMUNOSTAINING TECHNIQUE

We used a double-immunostaining technique to analyze the distribution of bcl-2(+) B and T lymphocytes within the synovial membranes (SM) of 13 patients with rheumatic diseases: 11 with rheumatoid arthritis (RA) , 1 with ankylosing spondylitis (AS), and 1 with osteoarthritis (OA). A high proportion (up to 50%) of the lymphocytes belonged to the B cel l subset. Most of both T and B lymphocytes were positive for the bcl-2 protein. In germinal centers B lymphocytes were also negative for bcl -2 protein expression, comparable to the situation in germinal centers of secondary lymphatic organs. We conclude that bcl-2(-) B lymphocyte s are submitted to antigen selection in the inflamed SMs while bcl-2 p rotein expression provides survival signals for their persistence in t he infiltrates. The expression of bcl-2 may be an important factor in protecting lymphocytes in SM from apoptosis by glucocorticoids, cytost atic drugs, and irradiation.