Cells of the monocyte-macrophage series in peripheral blood and synovial fluid in inflammatory arthritis. A preliminary study of cellular phenotype.

The phenotype of peripheral blood and synovial fluid cells of the monocyte-macrophage series was studied by FACS to extend previous immunohistological observations made in synovial membranes. The results of this preliminary study suggest that changes can be found in peripheral blood monocytes which might influence diapedesis and interaction with immune complexes. The phenotype of synovial fluid macrophages does not provide evidence of advanced maturation and is most consistent with rapid recruitment of the cells into the joint. Synovial fluid macrophages showed increased expression of the leukocyte integrin p150.95 which functions as an adhesion molecule and complement receptor. This is consistent with our previous observation of upregulation of this molecule on Mph in inflamed synovial membranes. This preliminary study has indicated areas for more detailed analysis with the aim of defining sequential changes in macrophage expression of functional surface molecules in inflammatory arthritis.