title: Inhibition of prostate cancer cell growth by activated eosinophils.
abstract: BACKGROUND
  Host Immune response to prostate cancer primarily involves the CTL and NK effector cells. Recent immunotherapeutic strategies incorporating cytokine genes into the tumor cell and/or dendritic cells have had encouraging results. In this study, we describe the inhibitory activity of a third potential effector cell, the eosinophil, against DU 145 and PC-3 prostate tumor cells growth in vitro.
  
  
  METHODS
  Subconfluent monolayer cultures of DU 145 and PC-3 cells were incubated with peripheral blood eosinophils from allergic or asthmatic individuals and also with eosinophil cultured supernatants. Newly established eosinophil cell lines were also studied. After harvesting, the plates were washed and stained with Hematoxylin/eosin (H/E) then photographed. The combination of monolayer cell growth inhibition and colony formation inhibition assays were used to evaluate eosinophil inhibitory activity. In the colony formation inhibition assay one hundred cells per well in 6-well plates were incubated overnight, after which peripheral blood eosinophils, conditioned media and cytokines, IL-4 and TNF-alpha were added. The plates were harvested after 10 days incubation period. Colonies were stained and counted.
  
  
  RESULTS
  Hypo- and hyperdense peripheral blood eosinophils from allergic and asthmatic individuals as well as eosinophil cell lines established from these subpopulations inhibited both DU 145 and PC-3 cell growth at 58-78% and 10-38%, respectively. IL-5 up-regulated eosinophil cell line activity by 21-24%. The conditioned media which contained the released mediators of activated eosinophils were potent in their actions on both DU 145 and PC-3, inhibiting colony formation by as much as 90-100%.
  
  
  CONCLUSIONS
  These results clearly demonstrate the inhibitory potential of activated eosinophils and their released "soup" of mediators and therefore support the hypothesis that eosinophils may participate in host response to prostate cancer together with CTLs and NK cells. Furthermore, this study offers insights into possible strategies for enhancing eosinophilic activity in prostate cancer.
authors.affiliation: Department of Microbiology, Howard University College of Medicine, Washington, DC 20060, USA. pfubert-harris@howard.edu
authors.forename: Paulette
authors.initials: P
authors.lastname: Furbert-Harris
authors.forename: Debra
authors.initials: D
authors.lastname: Parish-Gause
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Laniyan
authors.forename: Keith A
authors.initials: KA
authors.lastname: Hunter
authors.forename: Josephine
authors.initials: J
authors.lastname: Okomo-Awich
authors.forename: Theresa R
authors.initials: TR
authors.lastname: Vaughn
authors.forename: Kesha C
authors.initials: KC
authors.lastname: Forrest
authors.forename: Christina
authors.initials: C
authors.lastname: Howland
authors.forename: Abier
authors.initials: A
authors.lastname: Abdelnaby
authors.forename: Oladipo A
authors.initials: OA
authors.lastname: Oredipe
mesh_terms: D001249:Asthma / Q000097:blood; D002455:Cell Division / Q000187:drug effects; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004804:Eosinophils / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D006967:Hypersensitivity / Q000097:blood; D015847:Interleukin-4 / Q000494:pharmacology; D008297:Male; D011471:Prostatic Neoplasms / Q000276:immunology* / Q000473:pathology*; D013234:Stem Cells / Q000187:drug effects; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D017077:Culture Media, Conditioned; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4