To assess variation in peripheral blood B lymphocyte subsets in rheumatoid arthritis (RA).
B lymphocyte subsets in disease-modifying anti-rheumatic drug (DMARD)-naïve patients with RA (n = 30), patients with RA treated with DMARDs (n = 73) and healthy controls (n = 46) were analyzed by flow cytometry. Total B cells, total memory B cells, immunoglobulin M (IgM) memory B cells, switched memory B cells, non-switched memory B cells, CD21lo B cells, transitional B cells and plasmablasts were measured. Correlation with clinical and laboratory parameters was performed.
Total memory B cells, IgM memory B cells and non-switched memory B cells were reduced in RA patients at diagnosis compared to controls (P < 0.05). In patients with treated RA, there was a further reduction of total B cells, CD21lo cells, transitional B cells and plasmablasts, compared to controls (P < 0.05). The reduction in absolute numbers of total B cells, switched memory B cells, CD21lo cells, transitional B cells and plasmablasts in treated RA patients was significant (P < 0.05) even when compared to the DMARD-naïve patients. Only treatment responders (Disease Activity Score < 3.2) had reduced total B cells and absolute numbers of switched and IgM memory B cells (P < 0.05). In patients requiring leflunomide, total memory B cells, IgM memory B cells, non-switched memory B cells and absolute numbers of switched memory B cells were reduced compared with the remainder of the patient group (P < 0.05).
There is reduction of various B cell subsets in RA patients at diagnosis. Treatment with DMARDs leads to further reduction in additional B cell subsets without correction of the abnormalities. Reduction in individual subsets may predict RA patients requiring more intensive therapy.