Highly sensitive sandwich enzyme immunoassay for alpha-fetoprotein in human saliva.
To determine alpha-fetoprotein (AFP) in human saliva, a highly sensitive sandwich enzyme immunoassay for saliva AFP was developed. AFP standards and saliva samples were added into the wells of a polystyrene plate coated with goat IgG antibody against human AFP. After incubation, the wells were washed and horseradish peroxidase-labelled antibody was added. The enzyme activity specifically bound to the well was assayed using 3,3',5,5'-tetramethylbenzidine and hydrogen peroxide as substrate. The reaction was stopped by addition of 2 M sulphuric acid and the AFP concentration was determined from the absorbance at 450 nm. The minimum detectable concentration was 8 ng/L. The recovery of AFP mixed with human saliva was 91.1-102.4%. The within-assay and between-assay coefficients of variation were 6.5-8.9% and 7.6-10.8%, respectively. The assay correlated well with a radioimmunoassay for human AFP (r = 0.985, n = 13, P less than 0.001). The mean concentration of AFP in normal human saliva was 14.3 ng/L (SEM = 4.9 ng/L, n = 10) and significantly higher levels of saliva AFP were observed in hepatocellular carcinoma patients with positive serum AFP (mean 1367.8 ng/L, SEM 595.4 ng/L, n = 6; P less than 0.001). Strong correlation was observed between saliva AFP and serum AFP (r = 0.978, P less than 0.01, n = 13).
D000293:Adolescent; D000328:Adult; D006528:Carcinoma, Hepatocellular / Q000737:chemistry*; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008113:Liver Neoplasms / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D011897:Random Allocation; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry*; D012680:Sensitivity and Specificity; D000509:alpha-Fetoproteins / Q000032:analysis*
D000509:alpha-Fetoproteins