Measurement and partial characterization of the multiple forms of neurokinin A-like immunoreactivity in carcinoid tumours

J. M. Conlon, C. F. Deacon, G. Richter, W. E. Schmidt, F. Stöckmann, W. Creutzfeldt

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An antiserum raised against neurokinin A has been used to demonstrate storage and release of neurokinin A-like immunoreactivity by carcinoid tumours. The antiserum showed reactivity towards members of the tachykinin family of polypeptides in the order: neurokinin A > eledoisin > neurokinin B > kassinin > substance P > physalaemin but the magnitude of the cross-reactivity with substance P and physalaemin was < 1% of that of neurokinin A. A sensitive (IC50 238 fmol/ml; minimum detectable concentration, 9 fmol/ml) radioimmunoassay was set up using this antiserum. Extracts of metastatic tumour tissue from four patients with a primary carcinoid tumour in the midgut contained both neurokinin A-like immunoreactivity (NKA-LI) and substance P-like immunoreactivity (SP-LI). The concentrations (pmol/g wet weight) of NKA-LI and SP-LI in the tumours were: patient A 210, 201; patient B 2276, 6849; patient C 1198, 834 and patient D 424, 379. Analysis of the tumour extracts by reverse phase HPLC indicated that the NKA-LI was heterogeneous. Under two different conditions of chromatography, one component was eluted with the same retention time as neurokinin A. Two further components were more hydrophobic than neurokinin A but were not eluted with the retention time of neurokinin B. Analysis of these components by gel filtration indicated a molecular weight in the 3000-4000 range suggesting that they may be related to neuropeptide K, an N-terminally extended form of neurokinin A. NKA-LI and SP-LI were undetectable in the plasma of patients A and D but were elevated in patient B (NKA-LI 1005 ± 114; SP-LI 345 ± 85 fmol/ml) and patient C (NKA-LI 80 ± 31; SP-LI 21 ± 13 fmol/ml).

Original languageEnglish
Pages (from-to)183-196
Number of pages14
JournalRegulatory Peptides
Issue number2
Publication statusPublished (in print/issue) - Jan 1986


  • carcinoid syndrome
  • HPLC
  • radioimmunoassay
  • substance P
  • tachykinin


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