Characterisation of activated lymphocytes in the peripheral blood of patients with rheumatoid arthritis.

The extent and nature of lymphocyte activation in the circulation in rheumatoid arthritis (RA) was investigated. Peripheral blood lymphocytes (PBL) from RA patients and healthy controls were separated into a number of discrete fractions by density in discontinuous Ficoll density gradients. Low density (activated) lymphocytes were found at significantly higher levels in RA, particularly in patients with clinically active disease. Conversely, patients with clinically inactive RA had normal levels of activated lymphocytes. Lymphocyte populations within the ficoll gradient fractions were detected by E rosettes, staining for surface Ig, and by different avidities of EA binding. The activated population in RA was shown to be relatively depleted of T cells, enriched in surface Ig-bearing lymphocytes, and depleted of lymphocytes with high avidity EA binding. The evidence suggests that many of the activated PBL in RA are B blasts.