KE00075 is a solid phase sandwich Enzyme Linked-Immuno-Sorbent Assay (Sandwich ELISA). The PD1 ELISA kit is to be used to detect and quantify protein levels of endogenous PD1. The assay recognizes human PD1. An antibody specific for PD1 has been pre-coated onto the microwells. The PD1 protein in samples is captured by the coated antibody after incubation. Following extensive washing, another antibody specific for PD1 is added to detect the captured PD1 protein. For signal development, horseradish peroxidase (HRP)-conjugated antibody is added, followed by Tetramethyl-benzidine (TMB) reagent. Solution containing sulfuric acid is used to stop color development and the color intensity which is proportional to the quantity of bound protein is measurable at 450 nm with the correction wavelength set at 630 nm.