Immunoglobulin and Specific Antibody Synthesis in a Chronic Inflammatory Focus: Antigen-Induced Synovitis

Summary Incorporation of 14C amino acids into immunoglobulin and specific antibody (anti-BSA) was measured simultaneously in synovial membrane, buffy coat cells and spleen cells of rabbits, utilizing a coprecipitation technique. When immunoglobulin synthesis was measured in the synovial membranes of normal rabbits, small but significant amounts of newly-synthesized immunoglobulin were detected. In one of these animals undergoing a secondary response to BSA, 39.3% of the radioactive γ globulin synthesized by the synovium was accounted for as anti-BSA. At the same time, 28.4% and 67.2% of the immunoglobulin synthesized by the buffy coat and spleen-cells was also anti-BSA. It was concluded that antibody-forming cells of the recirculating lymphocyte pool enter normal tissue. A synovial inflammatory reaction was produced by three intra-articular injections of BSA. This was dependent on the appearance of systemic immunity to BSA since no synovitis developed in immunologically tolerant animals. When immunoglobulin and anti-BSA synthesis was measured in two rabbits with synovitis induced by such intra-articular injections, the fraction of γ globulin synthesized in synovium in the form of specific antibody was found to be 18.2% and 42.2%, respectively, while the fraction found for the spleen cells of the same animals was similar, i.e., 23.7% and 43.7%, respectively. This similarity in specific antibody synthesis in synovium and spleen indicated that the antibody-forming cell populations in both sites were similar. The synovial membranes of two rabbits given three intra-articular injections of PHA or SLS synthesized large amounts of γ globulin. This correlated well with the histologic appearance of the tissues, which were infiltrated with lymphocytes and plasma cells. When the amount of anti-BSA synthesized during a secondary response was measured in the synovial membranes, large amounts of radioactivity were accounted for as anti-BSA. The elevated level of synthesis of anti-BSA appeared to be a consequence of the accumulation of specifically committed cells in nonspecifically induced synovial inflammatory foci. These observations indicate (1) that immunoglobulin and specific antibody-synthesizing cells accumulate in chronic inflammatory foci produced by local injection of antigen or nonspecific inflammatory agents and (2) that the specificity of such antibody-producing cells reflects the overall immune status of the host.