title: Specific immunoassays for placental alkaline phosphatase as a tumor marker.
abstract: Human placental (hPLAP) and germ cell (PLAP-like) alkaline phosphatases are polymorphic and heat-stable enzymes. This study was designed to develop specific immunoassays for quantifying hPLAP and PLAP-like enzyme activity (EA) in sera of cancer patients, pregnant women, or smokers. Polyclonal sheep anti-hPLAP antibodies were purified by affinity chromatography with whole hPLAP protein (ICA-PLAP assay) or a synthetic peptide (aa 57-71) of hPLAP (ICA-PEP assay); the working range was 0.1-11 U/L and cutoff value was 0.2 U/L EA for nonsmokers. The intra- and interassay coefficients of variation were 3.7%-6.5% (ICA-PLAP assay) and 9.0%-9.9% (ICA-PEP assay). An insignificant cross-reactivity was noted for high levels of unheated intestinal alkaline phosphatase in ICA-PEP assay. A positive correlation between the regression of tumor size and EA was noted in a child with embryonal carcinoma. It can be concluded that ICA-PEP assay is more specific than ICA-PLAP, which is still useful to detect other PLAP/PLAP-like phenotypes.
authors.affiliation: Centro de Genética Molecular e Pesquisa do Câncer em Crianças (CEGEMPAC), Curitiba, PR, CEP 80030-110, Brazil.
authors.forename: Sérvio T
authors.initials: ST
authors.lastname: Stinghen
authors.forename: Juliana F
authors.initials: JF
authors.lastname: Moura
authors.forename: Patrícia
authors.initials: P
authors.lastname: Zancanella
authors.forename: Giovanna A
authors.initials: GA
authors.lastname: Rodrigues
authors.forename: Mara A
authors.initials: MA
authors.lastname: Pianovski
authors.forename: Enzo
authors.initials: E
authors.lastname: Lalli
authors.forename: Dodie L
authors.initials: DL
authors.lastname: Arnold
authors.forename: João C
authors.initials: JC
authors.lastname: Minozzo
authors.forename: Luis G
authors.initials: LG
authors.lastname: Callefe
authors.forename: Raul C
authors.initials: RC
authors.lastname: Ribeiro
authors.forename: Bonald C
authors.initials: BC
authors.lastname: Figueiredo