Background B lymphocyte stimulator factor (BLyS) is produced by wide range of cells of the immune system, and has proven to be a key factor in the selection and survival of B cells. BLyS is an important factor in the pathology of Systemic Lupus Erythematosus; elevated serum levels (≥20ng/mL) of soluble BlyS are at increased risk of flare.
Objectives Analyze the association among BLyS levels and clinical manifestations, as well as with SLE clinical activity.
Methods A cross-sectional and observational study was performed in patients diagnosed of SLE according to SLICC 2012 criteria and healthy controls. The study included a complete blood-test and clinical data collected by personal interview. Disease activity assessment was made by SLEDAI index and for the evaluation of chronic damage we used the validated SLICC damage index. Serum concentration of BLyS was analyzed by colorimetric methods. Lupus patients were dichotomized as high and low BLyS levels based on BLyS levels above 2 SD of the mean in healthy controls. Biostatistical analysis with R (3.3.2.) was performed.
Results Two hundred forty-two SLE patients were evaluated; 94.4% of them were female. Mean values were as follow: age at diagnosis 33.29±13.53 years, disease duration 15.82±10.56 years, SLEDAI 5.91±5.06, SLICC score 1.06±1.42, BLyS levels 1.811±1.757 ng/mL. The 22.5% of patients displayed increased BLyS levels. The 29.6% of total patients exhibit SLEDAI values up to 6, and only the 7% of them showed SLEDAI values up to 6 and high BLyS levels simultaneously. Higher BLyS levels were significantly correlated to the ANAs positivity (p=0.0006) and lymphopenia (p=0.01) but showed no correlation with hypocomplementemia neither anti-dsDNA. The statistical analysis did not yield differences in the clinical activity or accumulated damage between patients with lower and higher BLyS levels.
Conclusions In our series we observed a 22.5% of patients with high levels of BLyS, and the 7% of cases had BLyS high levels and SLEDAI>6. BLyS upregulation is related to ANAs positivity and lymphopenia. We have found no statistical evidences on the relationship of BLyS levels and clinical activity in our series of patients.
Disclosure of Interest None declared