BACKGROUND: Total PSA assays measure both complexed and non-complexed forms of PSA while free PSA assays only measure non-complexed forms. Free PSA is a mixture of isoforms including immature PSA (proPSA) with retained portions of the leader sequence (e.g. [-7], [-4], and [-2]proPSA) and nicked forms (BPSA). ProPSA isoforms in male sera have been associated with prostate cancer. This study characterized the analytical performance of a chemiluminescent immunoassay for [-2]proPSA.
METHODS: The Access Hybritech p2PSA assay is a sandwich immunoassay using an anti-[-2]proPSA monoclonal antibody attached to paramagnetic beads and an anti-PSA monoclonal antibody conjugated to alkaline phosphatase calibrated with recombinant [-2]proPSA. Analytical studies including sensitivity (CLSI EP17-A) and imprecision (CLSI EP5-A2) were performed.
RESULTS: The Access Hybritech p2PSA assay for [-2]proPSA had a dynamic range of 0.5 to 5000 pg/ml. The total CV of the assay was <7% for [-2]proPSA concentrations between 20 and 1000 pg/ml. The LOB was 0.50 pg/ml, LOD 0.69 pg/ml, and LOQ 3.23 pg/ml (20% CV). There was no hook effect up to 15,000 pg/ml. There was a <5% difference between calibrator and reagent lots and no interference from normal serum constituents.
CONCLUSIONS: The Access Hybritech p2PSA assay is a robust immunoassay for the measurement of serum [-2]proPSA.
Written by:
Sokoll LJ, Chan DW, Klee GG, Roberts WL, van Schaik RH, Arockiasamy DA, Broyles DL, Carlson CM, Mizrahi IA, Pierson TB, Tam JE Are you the author?
Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, MD 21287, United States
Reference: Clin Chim Acta. 2012 Aug 16;413(15-16):1279-83
doi: 10.1016/j.cca.2012.04.015
PubMed Abstract
PMID: 22542565