Comparative study on the level of B lymphocyte stimulator (BlyS) and frequency of lymphocytes between sero-negative and sero-positive rheumatoid arthritis patients

Aim To investigate the differences of B lymphocyte stimulator (BlyS) level and frequency of lymphocytes between sero-negative and sero-positive rheumatoid arthritis (RA) patients. Methods Sixty-nine RA patients were enrolled into this study and their clinical data were recorded. The BlyS levels in plasma, frequency of T and B lymphocytes, as well as T-helper (Th) subgroups were compared between sero-negative and sero-positive RA patients. Furthermore, the correlations between clinical features and immunological features were analyzed. Results The plasma BlyS level in sero-negative RA was higher compared to the sero-positive RA patients (1.73 +/- 1.71 vs. 0.99 +/- 0.59 ng/mL, P < 0.05) and osteoarthritis (OA) patients (1.73 +/- 1.71 vs. 0.59 +/- 0.12 ng/mL, P < 0.05). Plasma BlyS level was correlated with disease activity score (DAS-28, erythrocyte sedimentation rate and C-reactive protein), but had no correlation with the titers of rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP) antibodies. The patients with more advanced changes in X-rays had high plasma BlyS levels. No significant differences in the frequency of T lymphocytes, Th subpopulations and B lymphocytes in peripheral blood were observed between sero-negative and sero-positive RA patients. Conclusions Plasma BlyS level was correlated with disease activity and radiological progress, which indicates that plasma BlyS level may become a useful biological marker to reflect DAS and to predict RA prognosis.