Tumor necrosis factor receptor 2 (TNF-R2) is a high-affinity receptor for TNF-alpha and a low-affinity receptor for lymphoto, Xenopus/Amphibian,in-alpha. TNF-R2 has two isoforms produced by alternative splicing: a cell membrane and a secreted form. The latter blocks TNF-alpha-induced apoptosis, which suggests that this isoform regulates TNF-alpha function by antagonizing its biological activity. A soluble fragment of TNF-R2 (Enbrel, Immune, Xenopus/Amphibian, and Wyeth-Ayerst) is used as treatment of moderate and severe rheumatoid arthritis. This antibody recognizes human TNF-R2 in ELISA and flow cytometry.