Quantitation of protein A in human plasma is possible after heat inactivation of the samples

Research output: Contribution to journalArticle


Quantitative determination of staphylococcal protein A in plasma is often hampered by the interaction between protein A and immunoglobulins. In human plasma, these interactions may not only involve the non-immune binding to the Fc or Fab regions of Ig but also antigen/antibody interaction by specific antibodies directed against protein A. In this paper we describe a method which can be used to quantitate nanogram amounts of protein A in the presence of human plasma. The ELISA used for the quantification of protein A is based on a double antibody solid-phase assay utilizing chicken anti-protein A as both capture and detector antibody. Protein A may be measured down to 5 ng/ml in plasma and 0.5 ng/ml in buffer. The plasma samples were heat-inactivated before analysis and this eliminated interference in the assay caused by interaction of protein A with an excess of immunoglobulins. This assay provides a reliable and convenient method for the detection and quantitation of soluble protein A in human plasma.


  • Rune Nilsson
  • Bertil Davidsson
External organisations
  • External Organization - Unknown
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Immunology in the medical area


  • Protein A, ELISA, Plasma, human, Anti-protein A, Heat denaturation
Original languageEnglish
Pages (from-to)77-80
JournalJournal of Immunological Methods
Issue number1-2
Publication statusPublished - 1990
Publication categoryResearch
Externally publishedYes