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Journal of Biomedicine and Biotechnology
Volume 2006 (2006), Article ID 56087, 8 pages
Research Article

Specific Immunoassays for Placental Alkaline Phosphatase As a Tumor Marker

1Centro de Genética Molecular e Pesquisa do Câncer em Crianças (CEGEMPAC), Rua Agostinho Leão Júnior, 400 Alto da Glória, Curitiba, PR CEP 80030-110, Brazil
2Division of Pediatric Hematology and Oncology, Department of Pediatrics, Federal University of Paraná, Curitiba, PR CEP 80060-000, Brazil
3Institut de Pharmacologie Moléculaire et Cellulaire, CNRS UMR 6097, Valbonne, Sophia Antipolis 06560, France
4Meharry Medical College, Nashville, TN 37208, USA
5Center for Research and Production of Immunoglobulins (CPPI), Rua Targino da Silva s/n, Piraquara, PR CEP 83302-160, Brazil
6St. Jude Children’s Research Hospital, Department of Hematology and Oncology and International Outreach Program, 332 North Lauderdale, Memphis, TN 38105, USA
7Research Institute Pelé Pequeno Príncipe (IPPP), Avenida Silva Jardim, 1632 Água Verda, Curitiba, PR CEP 80250-200, Brazil

Received 23 December 2005; Revised 1 June 2006; Accepted 6 June 2006

Copyright © 2006 Sérvio T. Stinghen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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 0.111 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.