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. Binds to TRAF1, TRAF2, and TRAF3, but not TRAF5 and TRAF6. Binds through its C-terminus to SIVA1/SIVA. Expressed in lymph node, peripheral blood leukocytes and weakly in spleen. Up-regulated in peripherical mononuclear cells after antigen stimulation/lymphocyte activation.