Aim of the work: To assess serum levels of B lymphocyte stimulator (BLyS) and a proliferation-
inducing ligand (APRIL) to determine their correlations with disease activity in pediatric
systemic lupus erythematosus (pSLE) and juvenile idiopathic arthritis (JIA) patients.
Patients and methods: Twenty-nine pSLE patients and 33 JIA patients were recruited. SLE disease
activity was assessed using the systemic lupus erythematosus disease activity index (SLEDAI),
while the juvenile arthritis 27 joint disease activity score (JADAS-27) was calculated for JIA
patients. Serum samples were assayed for BLyS and APRIL by the enzyme linked immunosorbent
assay (ELISA).
Results: Serum BLyS and APRIL were elevated in both pSLE and JIA patients compared to
controls. Serum BLyS levels correlated with both SLE and JIA disease activity (p=0.042,
p = 0.019, respectively) whereas serum APRIL levels correlated positively with JADAS-27 and
inversely with SLEDAI (p= 0.001, p= 0.02, respectively). Elevated serum BLyS and APRIL were
significantly associated with a lower incidence of nephritis (p= 0.043, p= 0.016, respectively),
while elevated serum APRIL significantly associated with negative anti-dsDNA in pSLE patients
(p = 0.017). In JIA patients, both serum BLyS and APRIL were significantly associated with the presence of ANA (p= 0.008, p< 0.001, respectively), while high serum APRIL associated with the
presence of RF (p= 0.035). APRIL and BLYS levels correlated with each other positively in JIA
but inversely in pSLE patients.
Conclusion: Serum BLyS showed elevated levels that correlated significantly with pSLE and JIA
disease activity, accordingly anti-BLyS therapy might be of great benefit to offset disease flare. The
inverse correlations observed between APRIL with both BLyS and disease activity in pSLE patients
raises the possibility of being a down regulator of the disease process.