A 22 kDa human growth hormone specific enzyme-linked immunosorbent assay

A specific sandwich enzyme-linked immunosorbent assay (ELISA) was developed for human growth hormone (hGH) with molecular weight of 22 kDa (22k hGH). To prepare the 22k hGH specific antibody, a peptide (P-15) corresponding to residues 32-46 in 22k hGH was synthesized and used to immunize rabbits, because a 20k hGH variant was known to lack this peptide sequence. The assay method was developed using a combination of an anti P-15 polyclonal antibody (YK-2) coated on the microtiter well as a catching antibody and another polyclonal antibody against 22k hGH as a peroxidase-conjugated detecting antibody. The assay sensitivity was 1 ng/ml for 22k hGH, and cross-reactivity with other pituitary protein hormones as well as the 20k hGH variant was less than 0.01%, respectively. Furthermore, the 22k hGH content was measured precisely even in the presence of 20k hGH in this ELISA system.