Background: We developed a new enzyme-linked immunosorbent assay (ELISA) for ornithine carbamoyltransferase (OCT) and evaluated its usefulness.
Methods: Recombinant human OCT expressed in E. coli was used as an antigen to obtain the monoclonal antibodies for this assay.
Results: The reactivity of the antibodies to native OCT as well as recombinant OCT was enhanced at alkaline pH (8.5-10), and the assay's sensitivity was markedly improved. The antibodies react identically with native and recombinant OCT at pH 9.4. The dilution test showed a good linearity between dilution ratios and the concentrations. Different concentrations of OCT added were recovered on average at 90.4%. There was a good correlation between OCT protein levels in the ELISA and OCT enzyme activities (r=0.987, p<0.0001). A significant difference in the serum level of OCT was observed between chronic hepatitis patients (110.7+/-80 ng/ml) and healthy subjects (34.4+/-20.7 ng/ml) (p<0.0001). The serum levels of OCT between sexes differed significantly in the healthy subjects (p<0.0001).
Conclusions: Our newly established ELISA for OCT using monoclonal antibodies is sensitive enough for clinical application.