Increased EA-rosette formation by lymphocytes from patients with rheumatoid arthritis.

A modified method for estimating erythrocyte-antibody (EA) rosette formation of human peripheral blood lymphocytes (PBL) reveals consistent differences between rheumatoid arthritis (RA) patients tested and healthy control subjects. Using this method we find an average of 27 +/- 0-8% (standard error of mean) of PBL from 120 RA patients forming EA rosettes in contrast to only 6 +/- 0-6% of PBL from ninety-five healthy controls, and 7 +/- 0-9% from eighteen patients with systemic lupus erythematosus (SLE). This difference is not due to monocytes forming EA rosettes or to T-cell sheep red blood cell (SRBC) binding. The concentration of antibody used in our assay appears to highlight the RA-control differences--suggesting a possible qualitative difference in EA-binding capacity. We find no correlation between EA binding and disease duration or rheumatoid factor titre. The assay is susceptible to technical variation, and the effects of antibody concentration, lymphocyte to SRBC ratio, method of blood collection and lymphocyte-separation procedure have all been evaluated.