The kit is a competitive enzyme immunoassay for in vitro quantitative measurement of NKB in human serum, plasma and other biological fluids This ELISA kit uses Competitive-ELISA as the method. The microtiter plate provided in this kit has been pre-coated with Human NKB. During the reaction, Human NKB in the sample or standard competes with a fixed amount of Human NKB on the solid phase supporter for sites on the Biotinylated Detection Ab specific to Human NKB. Excess conjugate and unbound sample