TNF-beta (TNF-β) is a protein of 171 amino acids in length and N-glycosylated at position 62. Some cell lines secrete varying glycosylated forms of the factor that may differ also in their biological activities. The protein does not contain disulfide bonds and forms heteromers with LT-beta (Lymphotoxin-beta) that anchors the complexes in the membrane. TNF-β and TNF-α show approximately 30 percent sequence homology and bind to the same receptor, and murine and human TNF-β are highly homologous at 74 percent. The biological functions of human TNF-β (hTNF-β) include promoting lymphoid development, enhancing normal host resistance to infection, and inhibiting growth of malignant tumors. Elevated hTNF-b levels are usually related to Crohn's Disease, multiple sclerosis, juvenile rheumatoid adrenoleucodystrophy, hypercalcemia of adult T cell leukemia, arthritis, bulbous pemphigoid, non-Hodgkin's lymphoma, and pregnancy. TNF-β is cytolytic or cytostatic for many tumor cells and acts as a mitogen for B-lymphocytes. TNF-β is also a chemo-attractant for neutrophils, increases phagocytosis, and increases adhesion to the endothelium. TNF-b promotes the proliferation of fibroblasts and is likely involved in the wound healing processes in vivo. TNF-β not only induces the synthesis of GM-CSF, G-CSF, IL-1, but also acts as an anti-angiogenesis factor. Hemorrhagic necrosis of tumors induced by TNF-β in vivo is likely the result of an inhibition of the growth of endothelial cells. The TNF-β gene has a length of approximately 3 kb and contains four exons. The gene maps to human chromosome 6p23-6q12, which is approximately 1.2 kb apart from the TNF-α gene. The results obtained from the study of the TNF-β gene polymorphisms suggest that the gene may modify individual susceptibility to breast cancer in women. This hTNF-β ELISA Kit is a ready-to-use 3-hour solid phase immunoassay readily capable of measuring hTNF-β in the range of 0 to 4000 pg/mL in cell culture supernatant, serum and plasma. However, data collection for proliferation testing for hTNF-β detection will require additional days for completion. The assay has shown a specific reaction with hTNF-b and no cross-reactivity with various other cytokine superfamily proteins.