There are two popular theories regarding the pathogenesis of rheumatoid arthritis (RA). The first holds that the T cell, through interaction with an - as yet unidentified - antigen, is the primary cell responsible for initiating the disease as well as for driving the chronic inflammatory process. This theory is based upon the known association of RA with class II major histocompatability antigens, the large number of CD4+ T cells and skewed T cell receptor gene gouty arthritis gouty arthritis usage in the RA synovium. The second theory holds that, while T cells may be important in initiating the disease, chronic inflammation is self-perpetuated by macrophages and fibroblasts in a T-cell independent manner. This theory is based upon the relative absence of activated T cells phenotypes in chronic RA and the preponderance of activated macrophage and fibroblast phenotypes. Histopathology Synovium Cartilage Bone Synovial Cavity Synovium The synovium, in normal joints, is a thin delicate kidney pain symptom gouty arthritis lining that serves several important functions. (Slide) The synovium serves as an important source of nutrients for cartilage since cartilage itself is avascular. In addition, synovial cells synthesize joint lubricants such as hyaluronic acid, as well as collagens and fibronectin that constitute the structural framework of the synovial interstitium. 1. Synovial lining or intimal layer: Normally, this layer is only 1-3 cells thick (slide). In RA, this lining is greatly hypertrophied (8-10 cells thick) (slide). Primary cell arthritis gouty arthritis populations in this layer are fibroblasts and macrophages. 2. Subintimal area of synovium: This is where the synovial blood vessels are located; this area normally has very few cells. In RA, however, the subintimal area is heavily infiltrated with inflammatory cells, including T and B lymphocytes, macrophages and mast cells. The intense cellular infiltrate is accompanied by new blood vessel growth (angiogenesis). In RA, the hypertrophied synovium (also called pannus) invades and erodes contiguous bone and bone joints gouty arthritis cartilage. As such,
