Longitudinal analysis of serum B-Cell Activating Factor (BAFF) levels during pregnancy in women with systemic lupus erythematosus

Abstract Background Overexpression of B-Cell Activating Factor (BAFF) supports autoreactive B cells and prevents their deletion, which appears to be strongly linked to the pathogenesis of lupus. This study was developed to evaluate serum BAFF levels in pregnant women with systemic lupus erythematosus (SLE) throughout pregnancy, in addition to analyzing whether these levels are influenced by disease activity and the presence of preeclampsia (PE). Methods Blood samples were collected at 14–18, 24–26, 30–32, 34–36 and 38–40 weeks, frozen at -80 °C and subsequently analyzed for BAFF levels. Three study groups were considered: inactive SLE (Systemic Lupus Erythematosus Pregnancy Disease Activity Index [SLEPDAI] < 4), active SLE (SLEPDAI ≥ 4) and inactive SLE complicated by PE. Medians and interquartile ranges for BAFF levels were calculated, and linear models with random effects were applied. Results We analyzed 530 samples of 167 patients (inactive SLE: 117; active SLE: 36; inactive SLE and PE: 14). Considering all patients, mean serum BAFF decrease from weeks 14–18 to weeks 24–26 and 30–32, and rise again in weeks 34–36 and 38–40. There was no difference when the three study groups were compared. Applying the linear models with random effects, BAFF values were significantly lower in weeks 24–26, 30–32, and 34–36 compared to the values observed in week 14–18. Predicted BAFF levels in the preeclampsia group showed slightly higher values than in the other groups, but without statistical significance, and there was no difference in predicted values of patients with inactive and active SLE. Conclusions This study demonstrates that pregnant patients with SLE had lower mean serum BAFF levels in the second and third trimesters compared to the end of first trimester, but these levels were similar when patients with inactive SLE, active disease and inactive SLE with preeclampsia were compared.