title: Platelet-activating factor in human normal tears.
abstract: OBJECTIVE
  To measure the concentrations of platelet-activating factor (PAF) and lyso-PAF in tears of human eyes.
  
  
  METHODS
  Unilateral tear samples were collected from the conjunctival cul-de-sac of 12 healthy volunteers without any past histories of ocular surface diseases and 10 patients with allergic conjunctivitis (AC) by graduated disposable microcapillaries. C18:0-PAF, C18:0-lyso-PAF, C16:0-PAF, and C16:0-lyso-PAF levels were determined by liquid chromatography-tandem mass spectrometry (LC/MS/MS).
  
  
  RESULTS
  The concentrations of C18:0-PAF, C18:0-lyso-PAF, C16:0-PAF, and C16:0-lyso-PAF in tears from healthy volunteers were 0.44 +/- 0.39, 51.7 +/- 63.4, 61.9 +/- 75.9, and 10.7 +/- 14.7 ng/ml, respectively. Higher, but not significantly different, concentrations of all the four kinds of PAF molecules were detected in tears from AC patients. Significant correlations were demonstrated between the concentrations of C18:0-PAF and C18:0-lyso-PAF (r = 0.906; p < 0.01 in normal healthy volunteers and r = 0.939; p < 0.01 in AC patients), and between those of C16:0-PAF and C16:0-lyso-PAF (r = 0.944; p < 0.01 in normal healthy volunteers and r = 0.806; p = 0.015 in AC patients). Moreover, C18:0-PAF concentrations correlated significantly with those of C16:0-PAF (r = 0.885; p < 0.01 in normal healthy volunteers and r = 0.927; p < 0.01 in AC patients), while C18:0-lyso-PAF concentrations correlated significantly with those of C16:0-lyso-PAF (r = 0.972; p < 0.01 in normal healthy volunteers and r = 0.891; p < 0.01 in AC patients).
  
  
  CONCLUSIONS
  To our knowledge, this is the first report of the concentrations of different species of PAF (C18:0-PAF, C18:0-lyso-PAF, C16:0-PAF, and C16:0-lyso-PAF) in human tears.
authors.affiliation: Machida Hospital, Kochi, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Okumura
authors.forename: Kentaro
authors.initials: K
authors.lastname: Kojima
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Hashida
authors.forename: Yuji
authors.initials: Y
authors.lastname: Koura
authors.forename: Atsuki
authors.initials: A
authors.lastname: Fukushima
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Ueno
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002853:Chromatography, Liquid; D003233:Conjunctivitis, Allergic / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D009994:Osmolar Concentration; D010972:Platelet Activating Factor / Q000031:analogs & derivatives* / Q000032:analysis* / Q000737:chemistry; D020033:Protein Isoforms / Q000032:analysis; D013666:Tears / Q000737:chemistry*
chemical_list: C029271:O-deacetyl platelet activating factor; D010972:Platelet Activating Factor; D020033:Protein Isoforms