Synovial fluid lymphocytes differ from peripheral blood lymphocytes in patients with rheumatoid arthritis.

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Abstract
Peripheral blood (PBL) and synovial fluid lymphocytes (SFL) from 12 patients with rheumatoid arthritis (RA) were analyzed using monoclonal antibodies that detect specific T cell surface antigens (OKT3, OKT4, OKT8, SC1) and antigens associated with lymphocyte activation (anti-Ia, OKT10, B3/25). RA patients' PBL contained 1010 +/- 74 OKT4+ and 401 +/- 62 OKT8+ cells/mm3 (ratio OKT4+/OKT8+ = 2.4 +/- 0.3). In contrast, SFL from these patients exhibited a significantly different proportion of T cell subsets (ratio OKT4+/OKT8+ = 1.1 +/- 0.5) (p less than 0.0001) with 630 +/- 180 OKT4+ and 595 +/- 225 OKT8+ cells/mm3. Synovial fluid contained significantly more activated T cells based on the presence of Ia-positive T cells (19 +/- 5%) and reactivity with antibody OKT10 (49 +/- 7%) compared with RA-PBL (8 +/- 3% Ia-positive T cells and 13 +/- 6% OKT10+). Compared with RA-PBL, normal PBL contained an elevated number of OKT8+ cells (610 +/- 48/mm3), a similar number of OKT4+ cells (1040 +/- 86/mm3), and a lower percentage of activated lymphocytes (3 +/- 2% Ia-positive T cells and 10 +/- 8% OKT10+ cells). SFL, RA-PBL, and normal PBL all showed less than 3% cells reactive with antibody B3/25 (anti-transferrin receptor antibody), a marker found on in vitro activated T cells. These findings demonstrate that the lymphocytes at the site of inflammation differ significantly from the lymphocytes present in the peripheral blood of the same patients. RA patients had a small but significant decrease in the number of OKT8+ cells/mm3 compared with normal PBL (p less than 0.01), suggesting that this lymphocyte subset may home to synovial tissues, where it becomes activated.