In this LH ELISA Assay Kit, the LH calibrators, the patient specimens and/or the controls (containing the native Antigens) are first added to streptavidin coated wells. Then monoclonal biotinylated and enzyme labeled antibodies are added and the reactants mixed: these antibodies have high affinity and specificity and are directed against distinct and different epitopes of LH. A reaction between the various LH antibodies and native LH occurs in the microwells without competition or steric hindrance forming a soluble sandwich complex. The interaction is illustrated in the following equation: ka EnzAb + AgLH + BtnAb(m) ? EnzAb - AgLH-BtnAb(m) k-a BtnAb(m) = biotinylated monoclonal antibody (excess quantity) AgLH = native Antigens (variable quantity) EnzAb = enzyme labeled antibody (excess quantity) EnzAb-AgLH-BtnAb(m) = Antigens-antibodies sandwich complex ka = rate constant of association k-a = rate constant of dissociation Simultaneously, the complex is deposited to the well through the high affinity reaction of streptavidin and biotinylated antibody. This interaction is illustrated below: EnzAb -AgLH-BtnAb(m) + StreptavidinC.W. ???? Immobilized complex Streptavidin C.W. = streptavidin immobolized on well. Immobilized complex = antibodies-Antigens sandwich bound. After equilibrium is attained, the antibody-bound fraction is separated from unbound Antigens by a washing step. The enzyme activity in the antibody-bound fraction is directly proportional to the native Antigens concentration. The activity of the enzyme present on the surface of the well quantitated by reaction with a suitable substrate to produce colour. By utilizing several different calibrators of known Antigens values, a dose response curve can be generated from which the Antigens concentration of an unknown can be ascertained. Sample Types: serum, plasma. Range: 5 - 200 mIU/ml. Sensitivity: 0.22 mIU/ml. Time: 1.5 hours ? Luteinizing hormone (LH) is a glycoprotein consisting of two subunits with a molecular mass of 30,000 daltons. The α-subunit is similar to other pituitary hormones [follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH) and chorionic gonadotropin (HCG)] while the β-subunit is unique. The β-subunit confers the biological activity to the molecule. The α-subunit consists of 89 amino acid residues while the β-subunit contains 129 amino acids. The carbohydrate content is between 15% and 30%. The clinical usefulness of the measurement of luteinizing hormone (LH) in ascertaining the homeostasis of fertility regulation via the hypothalamic - pituitary - gonadal axis has been well established (1,2). In addition, the advent of in vitro fertilization (IVF) technology to overcome infertility associated problems has provided the impetus for rapid improvement in LH assay methodology from the technically demanding bioassay (3) to the procedurally simple and rapid immunoenzymometric assays.