Our principal findings are that in JIA, CXCL10/IP-10 is strongly expressed in synovial membranes and is released into synovial fluid (SF), where it exerts a definite chemotactic activity on CXCR3+ T-cell clones and on T cells purified from SF; and that there is an accumulation of CXCR3 expressing T lymphocytes from the bloodstream to the synovial fluid and membrane. The gene discussed is CXCL10; the disease is juvenile idiopathic arthritis.