Recruitment of lymphoblasts derived from peripheral and intestinal lymph to synovium and other tissues in normal rats and rats with adjuvant arthritis

Recruitment of [125I]iododeoxyuridine-labeled syngeneic lymphoblasts from thoracic duct (TD) lymph into periarticular tissues has been examined after intravenous administration to normal rats and to rats with adjuvant-induced arthritis. Uptake of label was observed in the inflamed paws of arthritic rats and cells were located in synovium and periarticular bone marrow by autoradiography. Uptake was greater with lymphoblasts from donors in the late prodromal phase of adjuvant-induced arthritis (arthritic donors) than from normal donors. With arthritic donors, recruitment of lymphoblasts from TD lymph was greater than from mesenteric duct lymph, suggesting that most of the joint-seeking lymphoblasts in arthritic rats arose in peripheral lymphoid tissues. Lymphoblasts from arthritic donors were also detected in the synovium of paws from normal rats. Recovery of lymphoblasts was monitored in other tissues; this revealed, in arthritic recipients, competition among extra-articular sites of inflammation (adjuvant injection site, draining lymph nodes, and lymph nodes draining affected joints), the lungs, and the inflamed synovium for recruitment of lymphoblasts from arthritic donors. In contrast, while some lymphoblasts from normal donors were recruited to inflamed joints, the small intestine was the main site of recruitment. The results reflect the known propensity of T lymphoblasts generated in peripheral lymphoid tissues to enter inflamed tissues. However, some mesenteric duct lymphoblasts also entered inflamed synovium. The observed pattern of recruitment of lymphoblasts to synovium is pertinent to the pathogenesis of arthritis, the potential roles of arthritogenic and bystander lymphocytes and the known links between the joints and inflammation in the intestine.