title: Low Levels of Exhaled Surfactant Protein A Associated With BOS After Lung Transplantation.
abstract: BACKGROUND
  There is no clinically available marker for early detection or monitoring of chronic rejection in the form of bronchiolitis obliterans syndrome (BOS), the main long-term complication after lung transplantation. Sampling and analysis of particles in exhaled air is a valid, noninvasive method for monitoring surfactant protein A (SP-A) and albumin in the distal airways.
  
  
  METHODS
  We asked whether differences in composition of exhaled particles can be detected when comparing stable lung transplant recipients (LTRs) (n = 26) with LTRs who develop BOS (n = 7). A comparison between LTRs and a matching group of healthy controls (n = 33) was also conducted. Using a system developed in-house, particles were collected from exhaled air by the principal of inertial impaction before chemical analysis by immunoassays.
  
  
  RESULTS
  Surfactant protein A in exhaled particles and the SP-A/albumin ratio were lower (P= 0.002 andP= 0.0001 respectively) in the BOS group compared to the BOS-free group. LTRs exhaled higher amount of particles (P< 0.0001) and had lower albumin content (P< 0.0001) than healthy controls.
  
  
  CONCLUSIONS
  We conclude that low levels of SP-A in exhaled particles are associated with increased risk of BOS in LTRs. The possibility that this noninvasive method can be used to predict BOS onset deserves further study with prospective and longitudinal approaches.
authors: Department of Respiratory Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors: Petrea A
authors: PA
authors: Ericson
authors: Department of Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors: Ekaterina
authors: E
authors: Mirgorodskaya
authors: Department of Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors: Oscar S
authors: OS
authors: Hammar
authors: Department of Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors: Emilia A
authors: EA
authors: Viklund
authors: Department of Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors: Ann-Charlotte R
authors: AR
authors: Almstrand
authors: Department of Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors: Per J-W
authors: PJ
authors: Larsson
authors: Department of Respiratory Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors: Gerdt C
authors: GC
authors: Riise
authors: Department of Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors: Anna-Carin
authors: AC
authors: Olin