The monoclonal antibody 5N reacts with Tumor Necrosis Factor alpha (TNF-alpha). Tumor necrosis factor-alpha (TNF-alpha), a homotrimeric 17 KD protein, is a potent mediator of inflammatory and metabolic functions. TNF-alpha was originally detected as a highly cytotoxic cytokine for tumor cells, it causes tumor necrosis in vivo and shows cytolytic activity against tumor cells in vitro. Further TNF-alpha has been implied as central mediator in shock induced by gram negative micro-organisms.The cytokine TNF-alpha is found to be a central mediator in many inflammatory and immunological processes: it can be induced by various products of micro-organisms and by various cytokines but it also induces on its turn the production of many cytokines.Signal transduction occurs via two types of TNF-receptors, the TNF-receptors I and II. The receptors differ strongly in their intra-cellular signaling pathways.The TNF-alpha trimer interacts with either of the two types of TNF-R leading to receptor cross-linking.The monoclonal antibody 5N cross-reacts and cross-neutralizes all monkey species TNF-alpha, except pig-tail macaque. With affinity about two orders lower it recognizes bovine and canine TNF-alpha.