Neutrophils-derived Parameters as Cost-effective Inflammatory, Disease Activity Marker in Systemic Lupus Erythematosus (SLE) and Role in Prediction of Lupus Nephritis

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease with various clinical manifestations and approximately 50% of the SLE patients develop lupus nephritis (LN), which increases the risk of renal failure, cardiovascular diseases and overall survival. Evaluation of neutrophil-derived parameters (Neut-X, Neut-Y and Neut-Z) as an inflammatory, disease activity marker and as a predictor of nephritis in SLE patients. In this cross-sectional study, 3 ml K3EDTA blood was taken from 110 SLE patients presented in Department of Clinical Immunology to evaluate neutrophil-derived parameters in Sysmex XT2000i haematology analyser and their correlation with other inflammatory biomarkers like, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) as well as SLE disease activity index-2000 (SLEDAI-2K). 24-hours urine protein levels were also estimated as a marker of renal involvement. Records of renal biopsy were available in 73 SLE patients, who belonged to different morphologic classification of LN. After performing bivariate Spearman correlation analysis (SPSS software, version 26.0), Neut-X (measures cytoplasmic granularity by side scattering) and Neut-Z (vector sum of Neut-X and Neut-Y) showed a significant positive correlation ( r > 0.200, P < .05) with ESR, CRP and SLEDAI-2K while Neut-Y (measures nucleic acid content by sideward fluorescence) showed a significant negative correlation ( r > 0.200, P < .05) with ESR and CRP. Receiver-operating characteristic curve analysis was used to evaluate diagnostic value of 24-hour urine protein and predictive values of neutrophil-derived parameters for renal involvement in SLE patients. Among neutrophil-derived parameters, Neut-X was found to be the best predictor of renal dysfunction with highest AUC of 0.710 (95% CI: 0.604-0.816; cut-off: 1344.50; sensitivity: 84.7%; specificity: 50%) followed by Neut-Z with AUC of 0.707 (95% CI: 0.600-0.813; cut-off: 1403.67; sensitivity: 87.5%; specificity: 50%). Our study shows that neutrophil-derived parameters may be used as novel cost-effective, non-invasive biomarker of disease activity as well as for predicting renal involvement in SLE patients.