The Response of Human Peripheral Blood Mononuclear Phagocytes to Rheumatoid Arthritis

The maturity of peripheral blood mononuclear phagocytes (B-MPs) from patients with rheumatoid arthritis (RA), osteoarthritis (OA), and reference ("normal") 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 expectations, 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.