title: Toll-like receptor ligands reverse suppression of contact hypersensitivity reactions induced by epicutaneous immunization with protein antigen.
abstract: BACKGROUND
  Epicutaneous (EC) immunization with protein antigens has been shown to induce antigen nonspecific suppression of subsequent T cell-dependent contact hypersensitivity (CS) reactions after active immunization. The aim of this work was to test if EC application of Toll-like receptor (TLR) ligands together with protein antigen could reverse suppression of CS.
  
  
  METHODS
  Mice were EC immunized by applying gauze patches soaked with a solution of protein antigen alone or in the presence of crude bacterial material (bacterial lysates or heat-killed bacteria) or purified TLR ligands and then tested for CS response. To test if reversal of EC-induced suppression is antigen-specific, mice were patched with TNP- or OX-substituted mouse Ig alone or together with LPS and then tested for CS with corresponding or non-cross-reacting hapten. Influence of EC immunization on cytokine production by lymph node cells was measured by ELISA.
  
  
  RESULTS
  EC immunization with protein antigen induces antigen nonspecific suppression that can be reversed by crude bacterial material as well as purified TLR-2, TLR-3, TLR-4, and TLR-9 ligands. The effect of TLR-4 ligand LPS was not observed in the Tlr-4 mutant C3H/HeJ mouse, indicating that this effect was dependent upon intact TLR-4 signaling. Unlike the antigen nonspecific suppression of CS by EC immunization with antigen alone, the reversal of suppression by TLR ligands was specific for the protein antigen applied in the EC protocol.
  
  
  CONCLUSIONS
  Our results strongly suggest that EC immunization with protein antigen together with TLR ligands induces a particular antigen-specific cell population, akin to previously described contrasuppressor cells, which protects immune cells against the action of suppressor cells but have no direct influence on antigen nonspecific suppressor cells induced by antigen alone.
authors.affiliation: Department of Immunology, Jagiellonian University College of Medicine, Kraków, Poland.
authors.forename: Włodzimierz
authors.initials: W
authors.lastname: Ptak
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Bryniarski
authors.forename: Maria
authors.initials: M
authors.lastname: Ptak
authors.forename: Monika
authors.initials: M
authors.lastname: Majewska
authors.forename: Andrzej
authors.initials: A
authors.lastname: Gamian
authors.forename: Francis M
authors.initials: FM
authors.lastname: Lobo
authors.forename: Marian
authors.initials: M
authors.lastname: Szczepanik
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology*; D016207:Cytokines / Q000276:immunology; D003877:Dermatitis, Contact / Q000276:immunology* / Q000517:prevention & control; D000939:Epitopes / Q000276:immunology; D007114:Immunization / Q000379:methods*; D008024:Ligands; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008808:Mice, Inbred CBA; D010081:Oxazolone / Q000276:immunology; D012867:Skin / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D051193:Toll-Like Receptors / Q000276:immunology* / Q000378:metabolism; D014301:Trinitrobenzenes / Q000276:immunology
chemical_list: D000941:Antigens; D016207:Cytokines; D000939:Epitopes; D008024:Ligands; D051193:Toll-Like Receptors; D014301:Trinitrobenzenes; D010081:Oxazolone