Interleukin-6 (IL-6) is a pleotropic cytokine with pro-inflammatory activities. Many studies have demonstrated the key role that IL-6 could play in the immunopathology of systemic lupus erythematosus (SLE).The objective of our study was to assess the association of serum and urine levels IL-6 with lupus nephritis (LN) and disease activity. 

IL-6 was measured by a chimiluminescence technique in 156 patients diagnosed SLE. The sex ratio was 10 women to 1 man and the average age was 35.66 ± 8.85 years. LN was observed in 65% of patients.

A significant association was observed between urine IL-6 level and LN [23.65 vs 6.61 pg/ml, p = 0.013]. In addition, patients with active lupus had higher urine IL-6 values than those with non-active form ( 28.3 vs 9.3 pg/ml, P < 0.005). The study of the correlation of IL-6 urine values with the disease activity index (SLEDAI) revealed a significant association (P=0.001, r=0.264).

The mean plasma concentrations of IL-6 in active versus non-active patients were 10.22 vs 1.57pg/ml (p=0.000) and based on presence versus absence of LN: 9.23 vs 4.57 pg/ml, p=0.044, respectively.

IL-6 could be considered as a potential non-invasive marker for the evaluation of disease activity and diagnosis of LN.