High serum LL37 levels in anti-neutrophil cytoplasmic antibody-associated vasculitis patients. (A) Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) sera contained higher levels of LL37 than the healthy control (HC) sera (U = 829.00, **P <0.01). (B) AAV patients with crescentic glomerulonephritis (GN) showed higher levels of LL37 as compared with the noncrescentic GN AAV patients (**P <0.01) and the HCs (***P <0.001). Serum levels of LL37 in the patients without crescentic GN were also significantly increased compared with those in the HCs (##P <0.01). (C) Patients with high LL37 expression (>100.3 ng/ml) had a greater risk of having crescentic GN than patients with low LL37 expression (<100.3 ng/ml) (χ2 = 9.724, P = 0.002).