Background: Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by disturbance of the innate and adaptive immune systems with the production of autoantibodies by stimulated B lymphocytes. The BLyS protein (B lymphocyte stimulator) is secreted mainly by monocytes and activated T cells and is responsible for the proliferation, maturation and survival of B cells.

Objectivs: To study sera BLyS level and its clinical significance in Israeli lupus patients over time.

Methods: The study population included 41 lupus patients (8 males, 33 females; mean age 35.56 ± 15.35 years) and 50 healthy controls. The patients were followed for 5.02 ± 1.95 years. We tested 221 lupus sera (mean 5.4 samples/patient) and 50 normal sera for BLyS levels by a capture ELISA. Disease activity was determined by the SLEDAI score.

Results: Sera BLyS levels were significantly higher in SLE patients than in controls (3.37 ± 3.73 vs. 0.32 ± 0.96 ng/ml, P < 0.05). BLyS levels were high in at least one sera sample in 80.5% of the patients but were normal in all sera in the control group. There was no correlation between sera BLyS and anti-ds-DNA autoantibody levels. BLyS levels fluctuated over time in sera of lupus patients with no significant correlation to disease activity.

Conclusions: Most of our lupus patients had high sera BLyS levels, suggesting a role for BLyS in the pathogenesis and course of SLE. Our results support the current novel approach of targeting BLyS (neutralization by antibodies or soluble receptors) in the treatment of active lupus patients.