Abnormalities in bone marrow mononuclear cells in patients with rheumatoid arthritis.

We analyzed the cell surface phenotype and the function of mononuclear cells in peripheral blood and in bone marrow of patients with rheumatoid arthritis (RA). The monoclonal antibodies anti-CD45RA, anti-CD29 and anti-S6F1 identify the suppressor-inducer (CD4+CD45RA+), helper-inducer (CD4+CD29+) and killer-effector (CD8+S6F1+) subpopulations of lymphocytes, respectively. In patients with RA, peripheral blood samples showed the same percentage of CD4+CD45RA+, CD4+CD29+ and CD8+S6F1+ cells as seen in control subjects. In contrast, in the bone marrow of patients with RA we observed a significant decrease in CD4+CD45RA+ cells, a significant increase in CD8+S6F1+ cells compared with findings in peripheral blood and in bone marrow samples from control subjects. Consistent with the phenotypic changes observed, bone marrow T cells also showed functional abnormalities, since autologous mixed lymphocyte reaction-activated CD4 cells from bone marrow of patients with RA showed a decrease in suppressor-inducer activity and CD8+ cells activated by allogenic E- cell showed an increase in killer-inducer activity. The changes noted above may contribute to the immunologic abnormalities that occur in this disease and provide insight into the pathophysiology of RA.