Analysis of bcl-2+ lymphocyte subpopulations in inflammatory synovial infiltrates by a double-immunostaining...

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 cell 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 lymphocytes are submitted to antigen selection in the inflamed SMs while bcl-2 protein expression provides survival signals for their persistence in the infiltrates. The expression of bcl-2 may be an important factor in protecting lymphocytes in SM from apoptosis by glucocorticoids, cytostatic drugs, and irradiation.