Blood, synovial fluids and/or synovial tissues will be obtained from patients with rheumatoid arthritis and related chronic inflammatory arthritides. The synovial tissues will be obtained by one of the following methods: a) needle biopsy, or b) at the time of a total joint replacement or a therapeutic arthroscopic procedure. These materials will be utilized for laboratory studies of etiopathogenetic mechanisms of rheumatoid arthritis and related autoimmune joint diseases.