OriginalArticlePepsin,aBiomarkerofGastricAspirationinLungAllograftsAPutativeAssociationwithRejectionRachelStovold1,2,IanA.Forrest1,PaulA.Corris1,DesmondM.Murphy1,JaclynA.Smith3,SamDecalmer3,GailE.Johnson1,JohnH.Dark1,JeffreyP.Pearson2andChrisWard11AppliedImmunobiologyandTransplantationResearchGroup,InstituteofCellularMedicine,and2EpithelialResearchGroup,InstituteforCellandMolecularBiosciences,UniversityofNewcastle-upon-Tyne,Newcastle-upon-Tyne,UnitedKingdom;and3NorthWestLungResearchCentre,UniversityofManchester,Manchester,UnitedKingdomCorrespondenceandrequestsforreprintsshouldbeaddressedtoChrisWard,Ph.D.,InstituteofCellularMedicine,SchoolofClinicalMedicalSciences,WilliamLeechBuilding,NewcastleUniversity,FramlingtonPlace,Newcastle-upon-TyneNE24HH,UK.E-mail:HYPERLINK"mailto:chris.ward@ncl.ac.uk"chris.ward@ncl.ac.ukABSTRACTHYPERLINK"http://ajrccm.atsjournals.org/cgi/content/full/175/12/1298"\l"top"TOPABSTRACTHYPERLINK"http://ajrccm.atsjournals.org/cgi/content/full/175/12/1298"\l"SEC1"ATAGLANCECOMMENTARYHYPERLINK"http://ajrccm.atsjournals.org/cgi/content/full/175/12/1298"\l"SEC2"METHODSHYPERLINK"http://ajrccm.atsjournals.org/cgi/content/full/175/12/1298"\l"SEC3"RESULTSHYPERLINK"http://ajrccm.atsjournals.org/cgi/content/full/175/12/1298"\l"SEC4"DISCUSSIONHYPERLINK"http://ajrccm.atsjournals.org/cgi/content/full/175/12/1298"\l"BIBL"REFERENCESRationale:Humanlungtransplantationisatherapeuticoptionforselectedpatientswithadvancedcardiopulmonarydisease,butlong-termsurvivalislimitedbychronicrejection.Persistentacuterejectionandgastricaspirationhavebeenimplicatedasriskfactorsbutthereislittleornoevidencetodatethattheyareassociated.Objectives:Wehavetestedthehypothesisthatpepsin,amarkerofgastricaspiration,ispresentinlungtransplantrecipients,andthathighlevelsareassociatedwithbiopsy-diagnosedacuterejectionand/orbronchiolitisobliteranssyndrome.Methods:Levelsofbronchoalveolarlavage(BAL)pepsinweremeasuredbyELISAin36lungtransplantrecipients,4normalvolunteers,a