Quantitative assessment of human leukocyte antigen-G protein in amniotic fluid by a double-determinant enzyme-linked immunosorbent assay using anti-human leukocyte antigen-G-specific antibody '87G'

PROBLEM: The objective of this study was to establish an enzyme-linked immu nosorbent assay (ELISA) system, in an attempt to quantify the amount of hum an leukocyte antigen (HLA)-G protein in amniotic fluid. METHOD OF STUDY: We established a double-determinant ELISA system using the anti-HLA-G-specific mouse monoclonal antibody '87G' as a capture antibody and the horseradish-peroxidase-labeled rabbit anti-human beta 2-microglobul in antibody as a detection antibody. We then measured the concentration of HLA-G protein in amniotic fluid samples from nine normal second-trimester p regnant women and in serum samples from eight normal males. RESULTS AND CONCLUSION: HLA-G protein was detected in amniotic fluid at a c oncentration of 275 ng/ml (197-343 ng/ml) (median value and 95% confident r ange), whereas the concentration of HLA-G protein in male serum was below t he minimum detection level.