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Measurement of the noncomplexed free fraction of tissue inhibitor of metalloproteinases I in plasma by immunoassay

Author

  • MN Holten-Andersen
  • IJ Christensen
  • HJ Nielsen
  • Hans Lilja
  • G Murphy
  • V Jensen
  • N Brunner
  • T Piironen

Summary, in English

Background: We previously found differences in total concentrations of tissue inhibitor of metalloproteinases 1 (TIMP-1) in plasma from donors and cancer patients. Because TIMP-1 can exist in more than one molecular form, a new immunoassay to specifically detect free TIMP-1 was developed and concentrations were determined in plasma from healthy donors and colorectal cancer (CRC) patients. Methods: We established and validated an immunoassay for the specific measurement of free TIMP-1 that uses a polyclonal anti-TIMP-1 antibody for capture and a monoclonal anti-TIMP-1 antibody that binds only free TIMP-1 for detection of antigen. Plasma samples from healthy donors and CRC patients were assayed for free TIMP-1. Total TIMP-1 was measured by our previously published assay. Results: The mean (SD) concentrations of free TIMP-1 were similar in citrate [55.5 (11.5) mug/L] and EDTA plasma [58.9 (13.3) mug/L] from 76 donors (r(2) = 0.82). In 154 donors, the ratio of free TIMP-1 [mean (SD), 64.5 (18.0) mug/L] to total TIMP-1 [83.8 (19.8) mug/L] in EDTA plasma was 0.77. Plasma concentrations of free and total TIMP-1 correlated significantly to age (free, r(2) = 0.19; total, r(2) = .0.27; P < 0.0001), increasing 50% over an age span of 45 years. Free and total TIMP-1 were significantly increased in CRC patients (P < 0.0001), whereas the ratio of free to total TIMP-1 (mean, 0.58) was significantly lower than in donors. Conclusions: Most of the TIMP-1 in donor plasma is present in its free form, and free TIMP-1 increases with age. Free and total TIMP-1 are increased in CRC patient plasma, but the ratio of free to total TIMP-1 is significantly lower in these patients than in donors. (C) 2002 American Association for Clinical Chemistry.

Publishing year

2002

Language

English

Pages

1305-1313

Publication/Series

Clinical Chemistry

Volume

48

Issue

8

Document type

Journal article

Publisher

American Association for Clinical Chemistry

Topic

  • Biochemistry and Molecular Biology

Status

Published

Research group

  • Clinical Chemistry, Malmö

ISBN/ISSN/Other

  • ISSN: 0009-9147