Alterations on peripheral blood B-cell subpopulations in very early arthritis patients

Objective. To characterize circulating B-cell subpopulations of arthritis patients with <6 weeks of disease duration. Methods. Peripheral blood samples were collected from very early untreated polyarthritis patients, with <6 weeks of disease duration, for flow cytometric evaluation of B-cell subpopulations. Samples from patients who were later diagnosed as RA [very early RA (VERA)] were also collected 4–6 weeks after starting a low dose of prednisone (5–10 mg) and 4 months after reaching the minimum effective dose of MTX. A matched healthy group was used as a control. Results. VERA patients have a lower percentage of total peripheral blood memory B cells (CD19+CD27+) and a significant decrease in the frequency of circulating pre-switch memory B cells (CD19+IgD+CD27+) as compared with controls. Therapy with corticosteroids or MTX was unable to restore the normal frequencies of these B-cell subpopulations. A significant decrease in peripheral pre-switch memory B cells is equally observed in other early arthritis patients. Furthermore, no significant differences are found in the frequencies of CD4+ and CD8+ T cells in all patient groups. Conclusions. In very early polyarthritis patients, there is a reduction in circulating pre-switch memory B cells. The reasons that may account for this effect are still unknown. Short-term corticosteroids and MTX do not seem to have a direct effect on circulating B-cell subpopulations in VERA patients.