Do high sensitivity C-reactive protein and serum interleukin-6 levels correlate with disease activity in systemic lupus erythematosuspatients?

INTRODUCTION: Systemic Lupus Erythematosus (SLE) is an inflammatory autoimmune disease where an interplay between acute phase proteins and cytokines are involved in disease activation.

AIM AND OBJECTIVES: This case control study was performed to investigate interrelationship between high sensitivity C-reactive proteins (hs-CRP), Interleukin-6 (IL-6) levels and disease activity among SLE patients.

MATERIALS AND METHODS: One hundred forty one clinically diagnosed SLE cases were included and disease activity was noted by SLE Disease Activity Index (SLEDAI). Serum IL-6 levels were measure by cytokine multiplex assay. Serum hs-CRP, C3 and C4 levels were measure by nephelometer. The Pearson correlation test was used for correlation between hs-CRP, Il-6 and SLEDAI.

RESULTS: Based on SLEDAI, 126 patients (89.4 %) had active disease and 15 patients (10.6%) had inactive disease. Mean hs-CRP levels in SLE patients were significantly higher (12.1+ 11.5 mg/L) than controls (2.41+ 1.37 mg/L) (P < 0.0001). Hs-CRP levels among active SLE were significantly higher (13.5+ 11.4 mg/L) as compared with inactive SLE (4.4 + 2.9 mg/L) (P=0.0002). Similarly, IL-6 levels in SLE patients were significantly higher among active SLE (26.9 + 15.5 pg/ml) as compared with inactive SLE (13.9+ 10.2 pg/ml) (P=0.0001). An inverse correlation between Il-6 and hemoglobin levels between active and inactive SLE was noted (r=-0.46, P <0.0001).

CONCLUSION: This study suggests a good correlation between hs-CRP, IL-6 and SLE disease activity indicating their direct involvement in inflammatory conditions associated with disease.