Significance of cell kinetic studies in experimental allergic arthritis: participation of monocytes in injury and recovery of the inflamed synovial membrane.

Experimental allergic arthritis in guinea pig has been investigated as a model of immunosynovitis. The course of synovial injury and recovery is quantitatively estimated by microscopic and autoradiographic evaluation. Using 3-H-thymidine pulse and prelabeling techniques it has been shown, that bone marrow derived monocyte-macrophage cells play a major role in the histopathogenesis of this form of arthritis. Cell kinetic studies during the initiation of experimental synovitis support the hypothesis, that so-called lining cell hyperplasia is predominantly due to infiltration by blood monocytes, which during the stage of recovery contribute to a secondary lining cell layer. The early bone and cartilage erosions are additional lesions, which appear to be dependent on the monocyte-macrophage system.