Quantitative changes in peripheral blood lymphocytes in erosive rheumatoid arthritis patients treated with methotrexate. Correlation with disease activity.

In order to better understand the immunological mechanisms involved in the pathogenesis of rheumatoid arthritis (RA), the level of various lymphocyte subsets in the peripheral blood of 29 patients with erosive RA was determined. All the patients were treated with methotrexate for 2 years. The total number and the proportion of CD3 cells, CD3+CD4+ and CD3+CD8+ cells did not change during the study. The initially increased level of CD19+ B-cells and CD19+CD5+ cells decreased during the treatment. The percentage of CD3-CD16+ natural killer cells was not affected by the treatment. At the inception of the study, we observed a deficiency of CD4+ CD45RA+ cells and the level of CD3+CD29+ cells was slightly increased. During the treatment we noticed significant elevation of CD45RA cells. Consequently, the CD29/CD45RA ratio significantly decreased. We showed significant correlation between changes in disease activity and changes in the level of CD19+ cells and CD4+CD29+ cells. Our results suggest that low-dose methotrexate may affect immunocompetent cells. The lowering in the CD29+ subset population associated with depletion of CD19 B-cells after methotrexate therapy may limit abnormal CD4+ cell activation and reduce the migration of lymphocytes into inflamed synovium.