Detection of serum interleukin-18 level and neutrophil/lymphocyte ratio in patients with antineutrophil cytoplasmic antibody-associated vasculitis and its clinical significance.

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of autoimmune diseases. This study aimed to investigate the clinical significance of changes in interleukin-18 (IL-18) and neutrophil/lymphocyte ratio (NLR) in the pathogenesis of AAV and the impact of NLR on the prognosis of patients. The clinical data of 52 AAV patients (AAV group) who met the conditions of hospitalization, 30 patients with mild mesangial proliferative glomerulonephritis (disease controls), and 30 healthy volunteers (normal controls) in Nephrology Department of Liuzhou People's Hospital from May 2020 to August 2022 were selected. A total of 52 AAV patients were divided into active phase (>15 points) and remission phase (≤15 points) based on the Birmingham vasculitis activity score (BVAS). Serum IL-18 level was detected by enzyme-linked immunosorbent assay in three groups. Pearson product moment correlation analysis was performed to investigate the correlation between serum IL-18 levels and clinical laboratory indicators, and receiver operating characteristic (ROC) curve analysis was performed on serum IL-18, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) levels, and NLR in AAV patients. The levels of serum creatinine, parathyroid hormone, β2-microglobulin (β2-MG), ESR, CRP, and IL-18 in active stage of AAV were significantly higher than those in remission stage of AAV. Moreover, the serum IL-18 level of active AAV patients was significantly higher than that of disease control group ( P < 0.05). The levels of eGFR, hemoglobin, and complement C3 were significantly lower than those during the remission ( P < 0.05). Pearson product moment correlation analysis showed that serum IL-18 level in AAV patients was positively correlated with BVAS score and ESR level. The area under the curve of serum IL-18, NLR, CRP, ESR levels evaluated by ROC curve was 0.921, 0.899, 0.83, and 0.75, respectively. Kaplan-Meier survival curve showed that the cumulative survival rate of patients in low NLR group was significantly higher than that in high NLR group (68.36 vs 42.89%), with significant difference (Log-Rank = 6.745, P = 0.025 < 0.05). IL-18 may be adopted as one of the important biological markers to judge the disease of AAV, and the cumulative survival rate of patients with high NLR is low, which may be applied as an indicator to evaluate the poor prognosis of patients with AAV.