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Proteolysis of β-trace Protein?
Otolaryngology–Head and Neck Surgery (2005) 133, 310-311
LETTERS TO THE EDITOR Proteolysis of -trace Protein? Dear Editors,
Beta-trace Protein Text: New Guidelines for the Reliable Diagnosis of Cerebrospinal Fluid Fistula
We read with interest the article “-trace protein test: New guidelines for the reliable diagnosis of cerebrospinal fluid fistula” by Meco et al, from the November 2003 issue of Otolaryngology–Head and Neck Surgery. The TP test certainly will offer several diagnostic advantages over 2transferrin in that it is inexpensive, rapid, and potentially applicable to intra-operative use. The authors indicate nasal secretions can be collected at home and stored in a plastic tube for patients with intermittent cerebrospinal fluid leak. We wonder if the authors have serially studied nasal secretions to determine if CSF proteins undergo proteolysis after interacting with natural host defenses present in normal nasal secretions. Nasal mucus contains several proteolytic enzymes, and in patients with sinonasal infection, the offending bacteria may also effect proteolysis.1 We know that transferrin proteins typically undergo some degree of breakdown upon interaction with lymphocytes and passive immune mediators.2 Although the rate of proteolysis of 2-transferrin has not been studied, we believe proteolysis of CSF rhinorrhea may decrease sensitivity of this test. If -trace protein—a prostaglandin synthase—is more stable than 2-transferrin, this may be another diagnostic advantage of the new test. Thank you, Neil G. Hockstein, MD; Noam A. Cohen, MD, PhD; James N. Palmer, MD Department of Otolaryngology–Head and Neck Surgery Hospital of the University of Pennsylvania Philadelphia, PA
Dear Editors,
REFERENCES 1. Salathe M, Forteza R, Conner GE. Post-secretory fate of host defense components in mucus. Novartis Foundation Symposium 2000;248:20 – 6; discussion 27–37, 277– 82. 2. Britagan BE, Hayek MB, Doebbeling BN, et al. Transferrin and lactoferrin undergo proteolytic cleavage in Pseudomonas aeruginosa–infected lungs of patients with cystic fibrosis. Infect Immun 1993;61(12): 5049 –55.
doi:10.1016/j.otohns.2005.05.005
We appreciate the interest of Drs Hockstein, Cohen, and Palmer in our article and would like to add some notes to the discussion. The new TP test will certainly offer diagnostic advantages for the detection of cerebrospinal fluid (CSF) fistulas because of its superior sensitivity and short turnaround time. Concerning the comments on proteolysis of CSF proteins by natural host defense or bacteria in nasal secretion (NS), we agree that under certain conditions this could occur and have already investigated this issue during the evaluation period of the TP test. In their statement, the authors remarked that CSF proteins, when mixed up with NS, could undergo changes through proteolysis and might therefore not be suitable as a marker for CSF. At the very beginning of TP test evaluation we had to investigate preanalytic uncertainties (time of sample collection; suitable material for sample collection; centrifugation speed and time; storage, if necessary; etc.) Our experience (over many years) with 2-transferrin test1-5 had not shown any problems with proteolysis and as a result we assumed a comparable situation for TP. In order to be certain that these changes cannot significantly influence the test results, we have examined the long-term stability of TP in samples under different conditions (unpublished data). It must have been clear that the preanalytic influences do not significantly change the test results in a clinical situation as well. Therefore, in an experimental trial of 18 samples, we determined the TP amount immediately, at day 1, at day 3, and at day 7. Samples were stored at room temperature. Each sample was prepared by mixing the same amount of CSF with equal volumes of NS from healthy individuals, and from patients with acute bacterial or chronic sinusitis. No significant change was observed between the immediate and the firstday TP values. TP decrease between the immediate determination and the third and seventh days after incubation at room temperature was on average 5% (maximum 8%). Additionally, in the first 3 months of clinical TP test evaluation, all NS samples were reanalyzed either the next day or the third day after the first analysis in order to control or recognize any arising matrix problems caused by mac-
0194-5998/$30.00 © 2005 American Academy of Otolaryngology–Head and Neck Surgery Foundation, Inc. All rights reserved.
LETTERS TO THE EDITOR Proteolysis of -trace Protein? Dear Editors,
Beta-trace Protein Text: New Guidelines for the Reliable Diagnosis of Cerebrospinal Fluid Fistula
We read with interest the article “-trace protein test: New guidelines for the reliable diagnosis of cerebrospinal fluid fistula” by Meco et al, from the November 2003 issue of Otolaryngology–Head and Neck Surgery. The TP test certainly will offer several diagnostic advantages over 2transferrin in that it is inexpensive, rapid, and potentially applicable to intra-operative use. The authors indicate nasal secretions can be collected at home and stored in a plastic tube for patients with intermittent cerebrospinal fluid leak. We wonder if the authors have serially studied nasal secretions to determine if CSF proteins undergo proteolysis after interacting with natural host defenses present in normal nasal secretions. Nasal mucus contains several proteolytic enzymes, and in patients with sinonasal infection, the offending bacteria may also effect proteolysis.1 We know that transferrin proteins typically undergo some degree of breakdown upon interaction with lymphocytes and passive immune mediators.2 Although the rate of proteolysis of 2-transferrin has not been studied, we believe proteolysis of CSF rhinorrhea may decrease sensitivity of this test. If -trace protein—a prostaglandin synthase—is more stable than 2-transferrin, this may be another diagnostic advantage of the new test. Thank you, Neil G. Hockstein, MD; Noam A. Cohen, MD, PhD; James N. Palmer, MD Department of Otolaryngology–Head and Neck Surgery Hospital of the University of Pennsylvania Philadelphia, PA
Dear Editors,
REFERENCES 1. Salathe M, Forteza R, Conner GE. Post-secretory fate of host defense components in mucus. Novartis Foundation Symposium 2000;248:20 – 6; discussion 27–37, 277– 82. 2. Britagan BE, Hayek MB, Doebbeling BN, et al. Transferrin and lactoferrin undergo proteolytic cleavage in Pseudomonas aeruginosa–infected lungs of patients with cystic fibrosis. Infect Immun 1993;61(12): 5049 –55.
doi:10.1016/j.otohns.2005.05.005
We appreciate the interest of Drs Hockstein, Cohen, and Palmer in our article and would like to add some notes to the discussion. The new TP test will certainly offer diagnostic advantages for the detection of cerebrospinal fluid (CSF) fistulas because of its superior sensitivity and short turnaround time. Concerning the comments on proteolysis of CSF proteins by natural host defense or bacteria in nasal secretion (NS), we agree that under certain conditions this could occur and have already investigated this issue during the evaluation period of the TP test. In their statement, the authors remarked that CSF proteins, when mixed up with NS, could undergo changes through proteolysis and might therefore not be suitable as a marker for CSF. At the very beginning of TP test evaluation we had to investigate preanalytic uncertainties (time of sample collection; suitable material for sample collection; centrifugation speed and time; storage, if necessary; etc.) Our experience (over many years) with 2-transferrin test1-5 had not shown any problems with proteolysis and as a result we assumed a comparable situation for TP. In order to be certain that these changes cannot significantly influence the test results, we have examined the long-term stability of TP in samples under different conditions (unpublished data). It must have been clear that the preanalytic influences do not significantly change the test results in a clinical situation as well. Therefore, in an experimental trial of 18 samples, we determined the TP amount immediately, at day 1, at day 3, and at day 7. Samples were stored at room temperature. Each sample was prepared by mixing the same amount of CSF with equal volumes of NS from healthy individuals, and from patients with acute bacterial or chronic sinusitis. No significant change was observed between the immediate and the firstday TP values. TP decrease between the immediate determination and the third and seventh days after incubation at room temperature was on average 5% (maximum 8%). Additionally, in the first 3 months of clinical TP test evaluation, all NS samples were reanalyzed either the next day or the third day after the first analysis in order to control or recognize any arising matrix problems caused by mac-
0194-5998/$30.00 © 2005 American Academy of Otolaryngology–Head and Neck Surgery Foundation, Inc. All rights reserved.