Production of immunoglobulins and IgG rheumatoid factor and IgM rheumatoid factor by mononuclear cells derived from bone marrow bloods of rheumatoid arthritis patients

Mononuclear cells (MNC) from bone marrow bloods of patients with rheumatoid arthritis (RA) and osteoarthritis (OA) patients were obtained at total knee or hip replacement of the joints and determined for their capacity to produce immunoglobulins, IgG rheumatoid factor (IgGRF) and IgMRF in vitro. Bone marrow bloods were obtained from tibia or femur adjacent to the affected joints, and from iliac bone which was supposed to be intact control bone marrow. Immunoglobulins and RF were measured by ELISA. IgGRF and IgMRF produced by bone marrow MNC were significantly higher in RA than in OA. There were no significant differences of RF production between bone marrow adjacent to the affected joints and intact iliac bone marrow. IgGRF/IgG and IgMRF/IgM ratios were significantly greater in RA than in OA. IgMRF produced by RA bone marrow MNC correlated with serum RF levels of the corresponding patients, but not with serum CRP levels or clinical activity index. These results suggest that bone marrow MNC of RA patients produce high levels of RF and are responsible for elevated serum RF in RA patients.