Serum and Urinary Interleukin-6 in Assessment of Renal Activity in Egyptian Patients with Systemic Lupus Erythematosus

AIM OF THE WORK: This study investigates whether serum and urinary interleukin-6 (IL-6) represent an early marker of kidney involvement and assesses the difference between them and renal biopsy in lupus nephritis (LN). PATIENTS AND METHODS: A total of 60 systemic lupus erythematosus (SLE) patients were compared to 20 healthy controls. Urinary and serum IL-6 were measured in both patients and controls. In addition, renal biopsy was done prior or shortly after urine and blood sampling; the results were classified according to the International Society of Nephrology/Renal Pathology Society classification of LN by recording the activity score and chronicity score for each sample. RESULTS: There was a significant higher level of urinary IL-6 in the SLE patients with biopsy-proven LN than in those without LN and those of the control group. However, no significant difference was reported between the three groups as regards serum IL-6. A strong positive correlation was found between urinary IL-6 and renal disease activity based on the renal SLE disease activity index (SLEDAI) score with no significant correlation regarding the extra renal SLEDAI. Urinary IL-6 was positively correlated with renal biopsy results and with its activity scores but weakly correlated with the chronicity scores. CONCLUSION: Urinary IL-6 may provide a simple noninvasive potential marker of disease activity of renal involvement in adult patients with SLE.