Receptor for TNFSF18. Seems to be involved in interactions between activated T-lymphocytes and endothelial cells and in the regulation of T-cell receptor-mediated cell death. Mediated NF-kappa-B activation via the TRAF2/NIK pathway (By similarity). Binds to TRAF1, TRAF2, and TRAF3, but not TRAF5 and TRAF6 (By similarity). Binds through its C-terminus to SIVA1/SIVA. Preferentially expressed in activated T lymphocytes. Up-regulated in peripherical mononuclear cells after antigen stimulation/lymphocyte activation.