Analysis of lymphocyte subsets of bone marrow in patients with rheumatoid arthritis by two colour immunofluorescence and flow cytometry.

Lymphocyte subsets defined by monoclonal antibodies were investigated in bone marrow and peripheral blood of 17 patients with rheumatoid arthritis (RA); 13 patients with osteoarthritis or aseptic necrosis served as controls. Patients with RA were found to have a raised OKT 4/8 ratio both in bone marrow and peripheral blood in comparison with the controls. Furthermore, bone marrow of RA showed a lower percentage of OKT 8+ T cells than that of controls. The percentage of HLA-DR+ T cells was higher in bone marrow than in peripheral blood of RA, though a slightly lower percentage was detected in bone marrow than in peripheral blood of controls. Thus T cell subsets in bone marrow of RA differ significantly from those of controls. Patients with RA had a higher OKT 4/8 ratio and a higher percentage of HLA-DR+ T cells in bone marrow than controls, suggesting that T cell subsets in bone marrow of RA are in an immunologically activated state and that T cell subsets are affected by rheumatoid inflammation in bone marrow of RA.