title: Effects of nasal saline spray on human neutrophils.
abstract: BACKGROUND
  Nasal saline spray (NSS) used in the treatment of rhinitis and sinusitis often contains the preservative benzalkonium chloride (BKC). Previous studies have shown that corticosteroid nasal sprays and topical decongestants containing BKC damage respiratory mucosa, decrease mucociliary activity, and inhibit neutrophil functions in vitro.
  
  
  OBJECTIVE
  To evaluate the effects of NSS with BKC on human neutrophils.
  
  
  METHODS
  Prospective, basic science observations.
  
  
  METHODS
  Human neutrophils were exposed to NSS with BKC or to phosphate-buffered saline (PBS) at varying times and concentrations. The cells were examined for morphologic changes by light microscopy and for viability as determined by trypan blue exclusion. Lactate dehydrogenase levels were measured to quantify neutrophil cell lysis. In vivo morphologic changes were studied in neutrophils obtained from the oral mucosa in human volunteers who rinsed their mouths with NSS or PBS.
  
  
  RESULTS
  Neutrophils exposed to NSS concentrations as low as 15% showed near-total cell lysis, and neutrophils exposed to 20% NSS demonstrated no cell viability by trypan blue staining. Phosphate-buffered saline-exposed cells were unaffected. The release of lactate dehydrogenase from lysed neutrophils increased sharply at NSS concentrations higher than 10% but remained stable in PBS-exposed cells. All neutrophils isolated from NSS oral rinses were lysed, while a mean of 78% of neutrophils from PBS rinses showed normal morphologic structure.
  
  
  CONCLUSIONS
  Nasal saline spray with BKC is toxic to human neutrophils even at concentrations far lower than those found in commercially available preparations. Saline solutions without BKC appear to be safer alternatives, and additional studies are needed to determine the clinical significance of these findings.
authors.affiliation: Department of Otolaryngology--Head and Neck Surgery, Eastern Virginia Medical School and Children's Hospital of the King's Daughters, Norfolk, USA. meboston@worldnet.att.net
authors.forename: Mark
authors.initials: M
authors.lastname: Boston
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Dobratz
authors.forename: E Stephen
authors.initials: ES
authors.lastname: Buescher
authors.forename: David H
authors.initials: DH
authors.lastname: Darrow
mesh_terms: D000281:Administration, Intranasal; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D011310:Preservatives, Pharmaceutical / Q000494:pharmacology*; D011446:Prospective Studies; D012220:Rhinitis / Q000188:drug therapy; D012852:Sinusitis / Q000188:drug therapy; D012965:Sodium Chloride / Q000008:administration & dosage*
chemical_list: D001548:Benzalkonium Compounds; D011310:Preservatives, Pharmaceutical; D012965:Sodium Chloride; D007770:L-Lactate Dehydrogenase