title: Development of a quantitative bead capture assay for soluble IL-7 receptor alpha in human plasma.
abstract: BACKGROUND
  IL-7 is an essential cytokine in T-cell development and homeostasis. It binds to the IL-7R receptor, a complex of the IL-7Ralpha (CD127) and common gamma (CD132) chains. There is significant interest in evaluating the expression of CD127 on human T-cells as it often decreased in medical conditions leading to lymphopenia. Previous reports showed the usefulness of CD127 as a prognostic marker in viral infections such as HIV, CMV, EBV and HCV. A soluble CD127 (sCD127) is released in plasma and may contribute to disease pathogenesis through its control on IL-7 activities. Measuring sCD127 is important to define its role and may complement existing markers used in lymphopenic disease management. We describe a new quantitative assay for the measurement of sCD127 in plasma and report sCD127 concentrations in healthy adults.
  
  
  RESULTS
  We developed a quantitative bead-based sCD127 capture assay. Polyclonal CD127-specific antibodies were chosen for capture and a biotinylated monoclonal anti-CD127 antibody was selected for detection. The assay can detect native sCD127 and recombinant sCD127 which served as the calibrator. The analytical performance of the assay was characterized and the concentration and stability of plasma sCD127 in healthy adults was determined. The assay's range was 3.2-1000 ng/mL. The concentration of plasma sCD127 was 164+/-104 ng/mL with over a log variation between subjects. Individual sCD127 concentrations remained stable when measured serially during a period of up to one year.
  
  
  CONCLUSIONS
  This is the first report on the quantification of plasma sCD127 in a population of healthy adults. Soluble CD127 plasma concentrations remained stable over time in a given individual and sCD127 immunoreactivity was resistant to repeated freeze-thaw cycles. This quantitative sCD127 assay is a valuable tool for defining the potential role of sCD127 in lymphopenic diseases.
authors.affiliation: National HIV and Retrovirology Laboratories, Public Health Agency of Canada, Ottawa, Canada. sylvie_faucher@phac-aspc.gc.ca
authors.forename: Sylvie
authors.initials: S
authors.lastname: Faucher
authors.forename: Angela M
authors.initials: AM
authors.lastname: Crawley
authors.forename: Wendy
authors.initials: W
authors.lastname: Decker
authors.forename: Alice
authors.initials: A
authors.lastname: Sherring
authors.forename: Dragica
authors.initials: D
authors.lastname: Bogdanovic
authors.forename: Tao
authors.initials: T
authors.lastname: Ding
authors.forename: Michele
authors.initials: M
authors.lastname: Bergeron
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Angel
authors.forename: Paul
authors.initials: P
authors.lastname: Sandstrom
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000276:immunology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020395:Receptors, Interleukin-7 / Q000097:blood* / Q000276:immunology; D012016:Reference Values; D012995:Solubility
chemical_list: D000911:Antibodies, Monoclonal; D020395:Receptors, Interleukin-7; C415350:interleukin-7 receptor, alpha chain
references.citation: J Exp Med. 2006 Jul 10;203(7):1693-700
references.pmid: 16818676
references.citation: Int Immunol. 2007 Dec;19(12):1329-39
references.pmid: 17956896
references.citation: J Acquir Immune Defic Syndr. 2009 May 1;51(1):104-5
references.pmid: 19390329
references.citation: PLoS One. 2008 Aug 13;3(8):e2952
references.pmid: 18698349
references.citation: Br J Cancer. 1998 Mar;77(6):992-7
references.pmid: 9528846
references.citation: Nat Med. 2001 Jan;7(1):73-9
references.pmid: 11135619
references.citation: Exp Hematol. 1994 Mar;22(3):321-8
references.pmid: 8112430
references.citation: Cell Immunol. 2000 Mar 15;200(2):81-7
references.pmid: 10753499
references.citation: Genes Immun. 2008 Jan;9(1):1-6
references.pmid: 17928869
references.citation: J Immunol. 2006 Nov 1;177(9):6072-80
references.pmid: 17056533
references.citation: J Acquir Immune Defic Syndr. 2001 Dec 15;28(5):454-7
references.pmid: 11744834
references.citation: Eur J Hum Genet. 2003 Jul;11(7):509-15
references.pmid: 12825072
references.citation: Curr Drug Targets. 2006 Dec;7(12):1571-82
references.pmid: 17168832
references.citation: Cytokine. 2000 Nov;12(11):1597-608
references.pmid: 11052810
references.citation: Blood. 2000 Oct 15;96(8):2803-7
references.pmid: 11023514
references.citation: Immunol Rev. 2005 Feb;203:110-26
references.pmid: 15661025
references.citation: J Leukoc Biol. 2006 Aug;80(2):227-36
references.pmid: 16707558
references.citation: J Clin Invest. 2009 Apr;119(4):997-1007
references.pmid: 19287090
references.citation: J Exp Med. 2008 Jul 7;205(7):1701-14
references.pmid: 18573906
references.citation: J Acquir Immune Defic Syndr. 2006 Aug 15;42(5):537-44
references.pmid: 16837861
references.citation: Transplantation. 2002 Sep 15;74(5):623-9
references.pmid: 12352877
references.citation: J Immunol. 2004 Aug 1;173(3):1681-8
references.pmid: 15265897
references.citation: Clin Chem. 2004 Jul;50(7):1250-3
references.pmid: 15229158
references.citation: J Immunol Methods. 2007 Jan 30;319(1-2):41-52
references.pmid: 17173927
references.citation: AIDS. 2007 Jan 2;21(1):101-3
references.pmid: 17148974
references.citation: Immunol Lett. 1998 Mar;61(1):53-61
references.pmid: 9562375
references.citation: Nat Immunol. 2006 Jul;7(7):709-14
references.pmid: 16785889
references.citation: Eur J Immunol. 2006 Feb;36(2):336-44
references.pmid: 16421946
references.citation: J Autoimmun. 2008 Aug;31(1):52-8
references.pmid: 18406576
references.citation: Clin Chim Acta. 1999 Nov;289(1-2):89-97
references.pmid: 10556656
references.citation: Blood. 1990 Nov 15;76(10):1941-5
references.pmid: 1700727
references.citation: Eur J Immunol. 2005 Mar;35(3):738-45
references.pmid: 15724249
references.citation: J Immunol. 2009 Feb 1;182(3):1541-7
references.pmid: 19155502
references.citation: AIDS. 2005 Nov 18;19(17):1981-6
references.pmid: 16260904
references.citation: Am J Transplant. 2006 Dec;6(12):2851-60
references.pmid: 17062001
references.citation: J Immunol. 2005 Mar 1;174(5):2900-9
references.pmid: 15728501
references.citation: Mol Cell Biol. 1991 Jun;11(6):3052-9
references.pmid: 2038316
references.citation: Cell. 1990 Mar 23;60(6):941-51
references.pmid: 2317865
references.citation: Cytogenet Cell Genet. 2001;93(1-2):23-5
references.pmid: 11474172
references.citation: Mediators Inflamm. 2005 Aug 14;2005(3):121-30
references.pmid: 16106097
references.citation: Nat Genet. 2007 Sep;39(9):1083-91
references.pmid: 17660817
references.citation: Hepatology. 2006 Nov;44(5):1098-109
references.pmid: 17058243
references.citation: J Infect Dis. 2008 Nov 15;198(10):1466-73
references.pmid: 18847371
references.citation: Eur J Immunol. 1996 Jan;26(1):10-6
references.pmid: 8566050
references.citation: J Biol Chem. 2006 Jan 20;281(3):1612-9
references.pmid: 16284400
references.citation: AIDS. 2005 Dec 2;19(18):2077-86
references.pmid: 16284456
references.citation: J Immunol. 2005 Jun 1;174(11):6571-6
references.pmid: 15905493
references.citation: Eur J Immunol. 1994 Dec;24(12):2927-34
references.pmid: 7805718
references.citation: J Exp Med. 2006 Jul 10;203(7):1701-11
references.pmid: 16818678