Journal of Leukocyte Biology 37:221-230 (1985) The Response of Human Peripheral

The maturity of peripheral blood mononuclear phagocytes (B-MPs) from pa-tients with rheumatoid arthritis (RA), osteoarthritis (OA), and reference (“nor-mal”) subjects was compared. Mononuclear cell isolates from peripheral blood were separated on discontinuous gradients of Percoll into low density (more mature) and high density (less mature) subpopulations. Contrary to expecta-tions, the proportion of immature B-MPs in RA patients was found to be significantly lower than that in reference subjects. In RA patients with synovial effusions the proportion of immature B-MPs approached but did not exceed those found in reference subjects, despite the fact that 31 % of these patients displayed a peripheral blood monocytosis. It was concluded that the bone marrow precursor population had adapted to the long-term demand for B-MPs in the course of this chronic inflammatory disease. Key words: mononuclear phagocytes, rheumatoid arthritis, density, chronic Inflam-mation, maturatio