IMMUNOHISTOLOGIC STUDY OF T-CELL RECEPTOR DELTA-CHAIN EXPRESSION IN RHEUMATOID SYNOVIAL MEMBRANES

Lymphocytes expressing γδ T-cell receptors (TCRs) have been shown to be reactive to mycobacterial antigens as well as the so-called stress proteins. The detection of increased numbers of γδ cells in the synovial fluid and peripheral blood of some patients with rheumatoid arthritis has suggested a potential role for these lymphocytes in the pathogenesis of this disorder. Twenty-three rheumatoid synovial membranes were studied using immunohistology and monoclonal antibodies in an attempt to define the patterns of distribution of γδ T cells in rheumatoid synovitis. Consecutive sections were stained for T1(CD5), T4(CD4), T8(CD8), TAC(CD25), the δ-chain markers δTCR1 and δTCS1, and the β-chain marker βF1. Our results show some regional differences in the distribution of CD4 and CD8 cells, the former being prominent in the lymphocytic aggregates and the latter most prominent in diffuse infiltrates immediately adjacent to the synovial lining layer. All tissues showed extensive staining for βF1; an estimated average of more than 90% of T cells expressed αβ TCR. The majority of samples showed limited staining for both δ-chain antibodies, with 20 of the 23 tissues appearing to have less than 1% of T lymphocytes expressing these markers. Three tissues stained extensively for both δTCR1 and δTCS1 in particular areas of the section. In these areas, small perivascular lymphocytic aggregates appeared to be composed mainly of γδ cells. TAC staining was virtually absent in all areas and tissues. It was concluded that the majority of T lymphocytes infiltrating rheumatoid synovial membranes express αβ TCR. An occasional tissue will show an area of intense γδ-cell infiltration, the distribution of which suggests some form of clonal expansion. These areas may be the site of unique immunopathologic processes. © 1992.