title: Pleural fluid levels of interleukin-5 and eosinophils are closely correlated.
abstract: BACKGROUND
  The mechanisms responsible for the accumulation of eosinophils in pleural fluid are not fully understood. The purpose of this study was to evaluate the relationship between eosinophil accumulation and the levels of interleukin (IL)-5, IL-3, and granulocyte/macrophage colony-simulating factor (GM-CSF) in pleural effusions.
  
  
  METHODS
  We evaluated 30 patients with eosinophilic pleural effusions (eosinophil count > 10% nucleated cells in pleural fluid) and 10 patients with noneosinophilic pleural effusions. The patients with eosinophilic pleural effusions included 22 patients with post-coronary artery bypass graft surgery pleural effusions and 8 patients with eosinophilic pleural effusions caused by other causes. IL-5, IL-3, and GM-CSF in all pleural fluids were measured using enzyme-linked immunosorbent assay kits.
  
  
  RESULTS
  The mean level of IL-5 in eosinophilic pleural effusions (283.1 +/- 341.6 pg/mL) was significantly (p < 0.025) higher than that in the noneosinophilic effusions (28.2 +/- 19.0 pg/mL). The absolute eosinophil count and percentage correlated significantly with the level of IL-5 in all patients (r = 0.55, p < 0.001, and r = 0.54, p < 0.001, respectively). There was no significant correlation between IL-5 levels and RBC counts in all patients (r = 0.24, p > 0.05). GM-CSF and IL-3 levels were below the detectable range in all pleural fluids.
  
  
  CONCLUSIONS
  There is a significant relationship between the levels of IL-5 in pleural fluid and the total number and percentage of eosinophils in the pleural fluid. IL-5 seems to be related to the eosinophil accumulation associated with blood or air in the pleural space and other eosinophilic pleural effusions.
authors.affiliation: Department of Chest Diseases, Zagazig University Hospital, Zagazig, Egypt.
authors.forename: K H
authors.initials: KH
authors.lastname: Mohamed
authors.forename: Amany I
authors.initials: AI
authors.lastname: Abdelhamid
authors.forename: Y C Gary
authors.initials: YC
authors.lastname: Lee
authors.forename: Kirk B
authors.initials: KB
authors.lastname: Lane
authors.forename: Barrett
authors.initials: B
authors.lastname: Conner
authors.forename: Michael
authors.initials: M
authors.lastname: Hawthorne
authors.forename: Richard W
authors.initials: RW
authors.lastname: Light
mesh_terms: D004797:Enzyme-Linked Immunosorbent Assay; D004802:Eosinophilia / Q000175:diagnosis; D004804:Eosinophils / Q000166:cytology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000032:analysis; D006801:Humans; D007377:Interleukin-3 / Q000032:analysis; D015848:Interleukin-5 / Q000032:analysis*; D007958:Leukocyte Count; D010996:Pleural Effusion / Q000378:metabolism* / Q000473:pathology
chemical_list: D007377:Interleukin-3; D015848:Interleukin-5; D016178:Granulocyte-Macrophage Colony-Stimulating Factor