B-cell-attracting chemokine-1 (BCA-1/CXCL13) in systemic lupus erythematosus, its correlation to disease activity and renal involvement.

Systemic lupus erythematosus (SLE) is a prototype of systemic autoimmune disease in which cytokines such as B lymphocyte chemoattractant (BLC or CXCL13) may play important roles in pathogenesis. The aim of our study was to investigate the implications of CXCL13 in SLE diagnosis and its correlation with disease activity and renal involvement. The study included 50 adult female patients with SLE and 30 age-matched female healthy individuals serving as a control group. Patients' Group was further subdivided according to disease activity calculated by SLE Disease Activity Index (SLEDAI). All studied individuals were subjected to assessment of serum CXCL13 by ELISA. A highly significant stepwise progressive increase in CXCL 13 level was recorded through controls, inactive SLE and active disease (P < 0.01). Moreover, it correlated positively with SLEDAI and proteinuria (P < 0.01). At a cut- off level 80 pg/mL, CXCL13 could discriminate active SLE from inactive (AUC = 0.989, sensitivity 100% & specificity 96%). In conclusion, an increased level of CXCL13 is a distinctive feature in SLE. CXCL13 correlates with disease activity and renal involvement.