A monoclonal antibody to human protein S used as the capture antibody for measuring total protein S by enzyme immunoassay

A. Krachmalnicoff, S. Tombesl, C. Valsecchi, A. Albertini, P. M. Mannucci

Research output: Contribution to journalArticle

Abstract

Measurement of Protein S in human plasma is clinically important because a deficiency of this protein, which functions as a cofactor of the naturally occurring anticoagulant activated Protein C, is a risk factor for venous thromboembolism. We describe a two-site, enzyme-linked immunosorbent assay (ELISA) for measuring Protein S in which a monoclonal IgG directed against the calcium-independent conformation of Protein S is the capture antibody. The range of detection for the assay was 10 to 160 ng of Protein S per milliliter. The coefficients of variation were 4.6%-7.3% within-assay and 7.7%-10.1% between-assay. We compared this assay with an ELISA involving a polyclonal anti-Protein S rabbit IgG as capture antibody (I) and with Laurell's electroimmunoassay (II) to measure Protein S in plasma from 32 normal subjects and 121 patients or individuals expected to have low concentrations of total Protein S (full-term new-borns, pregnant women after the 18th week of gestation, patients with disseminated intravascular coagulation or liver cirrhosis, patients receiving therapy with warfarin, and patients with congenital Protein S deficiency). In general, the results obtained with the monoclonal antibody-based ELISA correlated well with those from I (r = 0.94), less well with those from II (r = 0.86).

Original languageEnglish
Pages (from-to)43-46
Number of pages4
JournalClinical Chemistry
Volume36
Issue number1
Publication statusPublished - 1990

Keywords

  • Endogenous anticoagulants
  • Heritable disorders
  • Protein C
  • Thromboembolism
  • Vitamin K

ASJC Scopus subject areas

  • Clinical Biochemistry

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