Characterization of the Immunocompetent Cells of Rheumatoid Synovium from Tissue Sections and Eluates

T lymphocytes positively identified by alphanaphthyl acetate esterase (ANAE) (70%) were localized in perivascular "cuffs" in rheumatoid synovia. ANAE-negative lymphocytes (B lymphocytes) were primarily within the reactive lymphoid centers, whereas intracellular Ig-expressing plasma cells were outside the centers. Lysozyme of diffuse ANAE expressing mononuclear phagocytes (5-15%) were diffusely dispersed, but were seldom found in the lymphoid centers. There were few granulocytes (10%). On elution, plasma cells and lymphocytes were lost. Most granulocytes and mononuclear phagocytes in the eluate were immunoglobulin-positive. The in situ architecture is compatible with active immunologic inflammation and T-dependent immunoglobulin synthesis.