title: Anti-IL-5 attenuates activation and surface density of β(2) -integrins on circulating eosinophils after segmental antigen challenge.
abstract: BACKGROUND
  IL-5 activates α(M) β(2) integrin on blood eosinophils in vitro. Eosinophils in bronchoalveolar lavage (BAL) following segmental antigen challenge have activated β(2) -integrins.
  
  
  OBJECTIVE
  To identify roles for IL-5 in regulating human eosinophil integrins in vivo.
  
  
  METHODS
  Blood and BAL eosinophils were analysed by flow cytometry in ten subjects with allergic asthma who underwent a segmental antigen challenge protocol before and after anti-IL-5 administration.
  
  
  RESULTS
  Blood eosinophil reactivity with monoclonal antibody (mAb) KIM-127, which recognizes partially activated β(2) -integrins, was decreased after anti-IL-5. Before anti-IL-5, surface densities of blood eosinophil β(2) , α(M) and α(L) integrin subunits increased modestly post challenge. After anti-IL-5, such increases did not occur. Before or after anti-IL-5, surface densities of β(2) , α(M) , α(L) and α(D) and reactivity with KIM-127 and mAb CBRM1/5, which recognizes high-activity α(M) β(2) , were similarly high on BAL eosinophils 48 h post-challenge. Density and activation state of β(1) -integrins on blood and BAL eosinophils were not impacted by anti-IL-5, even though anti-IL-5 ablated a modest post-challenge increase on blood or BAL eosinophils of P-selectin glycoprotein ligand-1 (PSGL-1), a receptor for P-selectin that causes activation of β(1) -integrins. Forward scatter of blood eosinophils post-challenge was less heterogeneous and on the average decreased after anti-IL-5; however, anti-IL-5 had no effect on the decreased forward scatter of eosinophils in post-challenge BAL compared with eosinophils in blood. Blood eosinophil KIM-127 reactivity at the time of challenge correlated with the percentage of eosinophils in BAL post-challenge.
  
  
  CONCLUSIONS
  IL-5 supports a heterogeneous population of circulating eosinophils with partially activated β(2) -integrins and is responsible for up-regulation of β(2) -integrins and PSGL-1 on circulating eosinophils following segmental antigen challenge but has minimal effects on properties of eosinophils in BAL. Dampening of β(2) -integrin function of eosinophils in transit to inflamed airway may contribute to the decrease in lung inflammation caused by anti-IL-5.
authors: Department of Biomolecular Chemistry, University of Wisconsin, Madison, WI, USA. mwjohansson@wisc.edu
authors: M W
authors: MW
authors: Johansson
authors: K A
authors: KA
authors: Gunderson
authors: E A B
authors: EA
authors: Kelly
authors: L C
authors: LC
authors: Denlinger
authors: N N
authors: NN
authors: Jarjour
authors: D F
authors: DF
authors: Mosher
mesh_terms: D000328:Adult; D019138:Antibodies, Blocking / Q000276:immunology / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology; D000941:Antigens / Q000276:immunology*; D001249:Asthma / Q000276:immunology / Q000378:metabolism; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D018821:CD18 Antigens / Q000276:immunology / Q000378:metabolism*; D004804:Eosinophils / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D000939:Epitopes / Q000276:immunology; D005260:Female; D006801:Humans; D015848:Interleukin-5 / Q000037:antagonists & inhibitors / Q000276:immunology*; D007958:Leukocyte Count; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D055815:Young Adult
chemical_list: D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D000941:Antigens; D018821:CD18 Antigens; D000939:Epitopes; D015848:Interleukin-5; D008562:Membrane Glycoproteins; C084882:P-selectin ligand protein