LAUSR

BACKGROUND The aim of this study was to evaluate neutrophil extracellular traps (NETs) in kidney transplant recipients (KTR) and their potential involvement in acute antibody-mediated rejection (AAMR). METHODS We studied 3 groups: KTR with AAMR (KTR-Cases, n = 14); KTR without any immunologic event (KTR-Controls, n = 14) and donors (n = 12). Spontaneous and lipopolysaccharide-induced NETosis were evaluated by immunofluorescence indirect (IFI) (NET/cells ratio). Plasmatic cH3-DNA complexes were evaluated by ELISA, (Optic Density Index - ODI). The expression of MPO and citrullinated histone 4 (cH4) was evaluated in renal biopsies. RESULTS We found an enhanced spontaneous NETosis in KTR regardless of whether they had rejection. The Nets/cells ratio in spontaneous NETosis was 0.203 (IQR 0.12-0.34) in Total-KTR and 0.094 (IQR 0.01-0.17) in donors, p = .011. Likewise, the ODI of cH3-DNA was 1.41 (IQR 0.94-1.72) in Total-KTR, and 0.95 (IQR 0.83-1.27) in donors, p = .019. KTR-Cases had the higher amount of NETs 1.70 (IQR 1.19-1.91). In two KTR-Cases, expression of MPO and cH4 was found in biopsies. CONCLUSIONS KTR show enhanced NETosis. This may indicate a permanent activation of neutrophils. Although more studies are needed, the higher amount of NETs and netting neutrophils in biopsies of KTR-Cases suggest a role of NETosis in AAMR.