Identification of a new receptor subtype for tumor necrosis factor-alpha.

Two distinct receptors, which bind both tumor necrosis factor-alpha and tumor necrosis factor-beta (TNF-alpha and TNF-beta), have been previously identified and cloned from transformed cells. The present study identifies a novel receptor subtype in normal human liver which binds TNF-alpha but not TNF-beta. TNF-alpha but not TNF-beta competes for 125I-TNF-alpha binding and incorporation into affinity-labeled complexes in human liver plasma membranes (HLPM). Antisera to the cloned receptors competed for 125I-TNF-alpha binding to plasma membranes isolated from various transformed cell lines but not to HLPM. However, mRNAs corresponding in size to both known TNF receptors were detected in liver RNA, making it likely that post-transcriptional modifications account for the TNF-alpha specificity of HLPM. These observations suggest that the effects of TNF-alpha and TNF-beta on some normal tissues may be more distinct than previously realized.