title: Persistence of apoptosis-resistant T cell-activating dendritic cells promotes T helper type-2 response and IgE antibody production.
abstract: Antigen-specific T cell-mediated apoptosis of dendritic cells (DCs) represents a unique down-regulatory mechanism that prevents the continuous activation of T cells by antigen-loaded DCs; this regulatory mechanism is impaired in allergy and as a consequence a large proportion of DCs tends to escape apoptosis following cognate interaction with CD4(+) T cells. However, the biological relevance of greater numbers of apoptosis-resistant DCs to the development of allergic IgE-mediated reactions remained to be determined. Here, we sought to investigate the in vitro and in vivo regulatory features of apoptosis-resistant DCs and to assess their role in host sensitization. Freshly isolated CD11c(+/hi)B220(-)DCs from ovalbumin (OVA)-sensitized, OVA-immunized and naïve Balb/c mice were cultured with OVA-specific T cells and levels of T cell-mediated DCs apoptosis assessed by flow cytometry. Surviving apoptosis-resistant DCs were then recovered and subsequently co-cultured with OVA-specific CD62L(hi)CD44(low) naïve T cells or passively transferred into naive syngenic recipients. In vitro profile of DC and T cell lymphokine production, chemokine receptors expression and in vivo, post-adoptive DC transfer T helper (T(H)) and IgE responses were assessed. Apoptosis-resistant DCs showed differential regulatory properties compared to their freshly isolated counterpart independent of the sensitization status of the donor. When co-cultured with naïve OVA-specific T cells, apoptosis-resistant DCs from either sensitized or immunized mice induced T cells that produced increased levels of IL-4 and reduced levels of IFN-gamma and showed increased expression of T(H)-2 related CCR4 and CCR8 chemokine receptors. Finally, adoptive transfer of apoptosis-resistant DCs, induced higher levels of OVA-specific IgE responses in absence of antigen challenge in syngenic recipients compared to freshly isolated DCs from both sensitized and immunized mice. These data would suggest that sensitization-associated increased numbers of apoptosis-resistant T cell-activating DCs contribute to the generation/maintenance of IgE-mediated allergic reactions.
authors.affiliation: GI Biology and Health Programme, Institute of Food Research, Norwich, United Kingdom.
authors.forename: Juan L
authors.initials: JL
authors.lastname: Arques
authors.forename: Mari
authors.initials: M
authors.lastname: Regoli
authors.forename: Eugenio
authors.initials: E
authors.lastname: Bertelli
authors.forename: Claudio
authors.initials: C
authors.lastname: Nicoletti
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D000917:Antibody Formation / Q000276:immunology*; D017209:Apoptosis; D002454:Cell Differentiation; D002469:Cell Separation; D002470:Cell Survival; D003713:Dendritic Cells / Q000276:immunology*; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D007114:Immunization; D007073:Immunoglobulin E / Q000276:immunology*; D016130:Immunophenotyping; D008213:Lymphocyte Activation / Q000276:immunology*; D008222:Lymphokines / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology; D018418:Th2 Cells / Q000166:cytology* / Q000276:immunology*
chemical_list: D000949:Histocompatibility Antigens Class II; D008222:Lymphokines; D007073:Immunoglobulin E; D010047:Ovalbumin