F2R and medical procedure: In brief, kidney transplant patient-derived IgG (KTx-IgG; from patients with allograft vasculopathy), but not KTx-IgG from patients without allograft vasculopathy or healthy-donor-derived control IgG (Con-IgG), stimulates GPCR-PAR-1-signaling-axis-dependent TNF-α secretion from HMECs and THP-1 monocytic cells.