Apolipoprotein A-I (ApoA1) is the major protein constituent of high density lipoprotein which is the densest of the lipoprotein aggregates. ApoA1 participates in the reverse transport of cholesterol from tissues to the liver and is a cofactor for lecithin cholesterol acyl tranferase. The ratio of ApoA1 to Apolipoprotein B (ApoB), the primary component of low density lipoprotein, is an effective predictor of cardiovascular disease. The sensitive quantitative measurement of total human ApoA1 antigen in plasma, serum, urine & other biological fluid samples is easily performed with this 96 well strip format ELISA kit. ApoA1 is present in human plasma and serum at a concentration of 0.75-1.6 mg/ml in adult males, 0.8-1.75 mg/ml in adult females, 0.38-1.06 mg/ml in newborns, and 0.6-1.67 mg/ml in children. The ratio of ApoA1/ApoB ranges from 0.85-2.24 in males and 0.76-3.23 in females. The assay measures total human ApoA1 in the 5-5000 ng/ml range. Samples giving human ApoA1 levels above 5000 ng/ml should be diluted in diluent before use. A 1:40,000 to 1:80,000 dilution for normal human plasma is suggested for best results. Human ApoA1 will bind to the affinity purified capture antibody coated on the microtiter plate. After appropriate washing steps, monoclonal anti-human ApoA1 primary antibody binds to the captured protein. Excess primary antibody is washed away and bound antibody is reacted with the peroxidase conjugated secondary antibody. Following an additional washing step, TMB substrate is used for color development at 450nm. A standard calibration curve is prepared along with the samples to be measured using dilutions of human ApoA1. Color development is proportional to the concentration of total ApoA1 antigen in the samples.All reagents and standards are provided in these ELISA kits.