Towards the development of an immuno MALDI (iMALDI) mass spectrometry assay for the diagnosis of hypertension

  • Jennifer D. Reid
  • Daniel T. Holmes
  • D. Randal Mason
  • Brinda Shah
  • Christoph H. Borchers
Focus: Affinity Mass Spectrometry


The renin-angiotensin-aldosterone system (RAAS) plays an essential role in the regulation of plasma volume and arterial blood pressure. One of the most common diseases of the RAAS is the autonomous production of aldosterone by the adrenal glands, caused by either bilateral adrenal hyperplasia or an aldosterone-producing adenoma. This condition, known as primary aldosteronism, is a treatable and often curable form of hypertension. The measurement of plasma renin activity (PRA), as determined by radioimmunoassay for angiotensin I is essential to the diagnosis of primary aldosteronism. However, accurate determination of PRA is often hampered by low plasma concentrations of angiotensin I. Here, we report the use of immuno-MALDI (iMALDI) as a highly sensitive and specific method for the absolute quantitation of angiotensin I in plasma. iMALDI permits concentration determination by affinity-capture of angiotensin I and a stable-isotopically labeled standard (SIS) peptide on immobilized anti-peptide antibodies. The affinity beads are placed on the MALDI target, permitting automated analysis of large numbers of patient samples. Pretreatment of the plasma is not required, and this method is suitable for the accurate determination of angiotensin I in whole plasma. The calibration curve generated using this method was linear over a 50-fold concentration range in plasma, with a correlation coefficient of 0.984. MS/MS sequence confirmation provides absolute specificity. The iMALDI angiotensin I assay, therefore, has the potential to be developed into a method for determining PRA that has advantages in time, in specificity, and in safety.


  1. 1.
    Chobanian, A. V.; Bakris, G. L.; Black, H. R.; Cushman, W. C.; Green, L. A.; Izzo, J. L. J.; Jones, D. W.; Materson, B. J.; Oparil, S.; Wright, J. T. J.; Roccella, E. J. Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. National Heart, Lung, and Blood Institute; National High Blood Pressure Education Program Coordinating Committee. Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension 2009, 42, 1206–1252.CrossRefGoogle Scholar
  2. 2.
    Don, B. R.; Schambelan, M.; Lo, J. C. Endocrine Hypertension. In Basic and Clinical Endocrinology, 7th ed; Lange Medical Books/McGraw Hill: Toronto, 2004; p. 414–438.Google Scholar
  3. 3.
    Jiang, J.; Parker, C. E.; Hoadley, K. A.; Perou, C. M.; Boysen, G.; Borchers, C. H. Development of an Immuno Tandem Mass Spectrometry (iMALDI) assay for EGFR diagnosis. Proteom. Clin. Appl. 2007, 1, 1651–1659.CrossRefGoogle Scholar
  4. 4.
    Jiang, J.; Parker, C. E.; Fuller, J. R.; Kawula, T. H.; Borchers, C. H. An Immunoaffinity Tandem Mass Spectrometry (iMALDI) Assay for Detection of Francisella tularensis. Anal. Chim. Acta 2007, 605, 70–79.CrossRefGoogle Scholar
  5. 5.
    Goodfriend, T. L.; Levine, L.; Fasman, G. D. Antibodies to Bradykinin and Angiotensin: A Use of Carbodiimides in Immunology. Science 1964, 144, 1344–1346.CrossRefGoogle Scholar
  6. 6.
    Bordeerat, N. K.; Georgieva, N. I.; Klapper, D. G.; Collins, L. B.; Cross, T. J.; Borchers, C. H.; Swenberg, J. A.; Boysen, G. Accurate Quantitation of Standard Peptides Used for Quantitative Proteomics. Proteomics 2009, 9, 3939–3944.CrossRefGoogle Scholar
  7. 7.
    Shah, B.; Reid, J. D.; Kuzyk, M. J.; Parker, C. E.; Borchers, C. H. Developing an iMALDI Method. Methods Mol. Biol. 2009, unpublished, (submitted for publication).Google Scholar
  8. 8.
    Poulsen, K.; Jorgensen, J. An Easy Radioimmunological Microassay of Renin Activity, Concentration, and Substrate in Human and Animal Plasma and Tissues Based on Angiotensin Trapping by Antibody. J Clin. Endocrinol. Metab. 1974, 39, 816–825.CrossRefGoogle Scholar
  9. 9.
    Reid, J. D.; Parker, C. E.; Borchers, C. H. Protein Arrays for Biomarker Discovery. Curr. Opin. Mol. Therapeut. 2007, 9, 216–221.Google Scholar
  10. 10.
    Warren, E. N.; Elms, P. J.; Parker, C. E.; Borchers, C. H. Development of a Protein Chip: A MS-Based Method for Quantitation of Protein Expression and Modification Levels Using an Immunoaffinity Approach. Anal. Chem. 2004, 76, 4082–4092.CrossRefGoogle Scholar
  11. 11.
    Warren, E. N.; Jiang, J.; Parker, C. E.; Borchers, C. H. A Method for the Absolute Quantitation Of Cancer-Related Proteins Using A MS-Based Peptide Chip. BioTechniques 2005, 38, S7-S11.CrossRefGoogle Scholar
  12. 12.
    Hartman, D.; Sagnella, G. A.; Chesters, C. A.; MacGregor, G. A. Direct Renin Assay and Plasma Renin Activity Assay Compared. Clin. Chem. 2004, 50, 2159–2161.CrossRefGoogle Scholar
  13. 13.
    Sealey, J. E.; Gordon, R. D.; Mantero, F. Plasma Renin and Aldosterone Measurements in Low Renin Hypertensive States. Trends Endocrinol. Metab. 2005, 16, 86–91.CrossRefGoogle Scholar
  14. 14.
    Locsei, Z.; Racz, K.; Patocs, A.; Kovacs, G. L.; Toldy, E. Influence of Sampling and Storage Conditions on Plasma Renin Activity and Plasma Renin Concentration. Clin. Chim. Acta 2009, 402, 203–205.CrossRefGoogle Scholar
  15. 15.
    Lijnen, P. J.; Amery, A. K.; Fagard, R. H. Endogenous Angiotensin I Concentration in Human Plasma. J. Lab. Clin. Med. 1978, 92, 353–362.Google Scholar
  16. 16.
    Shah, B.; Borchers, C. H. iMALDI: A Targeted Proteomics Approach to the Differentiation of EGFR and Its Isoforms. Proceedings of the 57th ASMS Conference on Mass Spectrometry and Allied Topics; Philadelphia, PA, May 31–June 4; 2009.Google Scholar

Copyright information

© American Society for Mass Spectrometry 2010

Authors and Affiliations

  • Jennifer D. Reid
    • 1
    • 2
  • Daniel T. Holmes
    • 3
  • D. Randal Mason
    • 1
    • 2
  • Brinda Shah
    • 1
    • 2
  • Christoph H. Borchers
    • 1
  1. 1.University of Victoria-Genome British Columbia Proteomics CentreUniversity of VictoriaVictoriaCanada
  2. 2.Department of Biochemistry and MicrobiologyUniversity of VictoriaVictoriaCanada
  3. 3.Department of Pathology and Laboratory MedicineUniversity of British ColumbiaVancouverCanada

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