Tumor necrosis factor receptor superfamily member 19L (TNFRSF19L), also known as Receptor expressed in lymphoid tissues and RELT, is a member of the TNF-receptor superfamily. TNFRSF19L is a single-pass type membrane protein and contains one TNFR-Cys repeat. TNFRSF19L is highly expressed in spleen, lymph node, thymus, peripheral blood leukocytes, bone marrow and fetal liver. It has been shown TNFRSF19L activates the NF-kappaB pathway and selectively binds TNF receptor-associated factor 1 (TRAF1). TNFRSF19L is capable of stimulating T-cell proliferation in the presence of CD3 signaling, which suggests its regulatory role in immune response.