Intracellular pathogens and professional phagocytes in reactive arthritis.

Reactive arthritis is a postinfectious complication which develops after certain infections, mostly gastrointestinal or urogenital. Antigenic structures of the causative microbes, but no live organisms, have been demonstrated in inflamed joints. The host factors as well as the microbial antigens responsible for the initiation of the arthritic process are unknown. The pathogenesis of reactive arthritis is discussed here with special reference to the intracellular life of the causative microbes and to monocytes/macrophages, which may be involved in early events of the arthritic process as well as in maintenance of the autoimmune type of responses.