Cayman's TNF-α assay is an immunometric sandwich ELISA that permits TNF-α measurements within the range of 3.9-250 pg/ml, typically with a limit of detection of 3.9 pg/ml. Inter- and intra-assay CV's of less than 5% can be achieved at most concentrations. This assay allows sensitive, specific analysis of TNF-α in serum or plasma.