ABSTRACT
IgE antigen complexes induce increased specific T cell proliferation and increased specific IgG production. Immediately after immunization, CD23(+) B cells capture IgE antigen complexes, transport them to the spleen where, via unknown mechanisms, dendritic cells capture the antigen and present it to T cells. CD23, the low affinity IgE receptor, binds IgE antigen complexes and internalizes them. In this study, we show that these complexes are processed onto B-cell derived exosomes (bexosomes) in a CD23 dependent manner. The bexosomes carry CD23, IgE and MHC II and stimulate antigen specific T-cell proliferation in vitro. When IgE antigen complex stimulated bexosomes are incubated with dendritic cells, dendritic cells induce specific T-cell proliferation in vivo, similar to IgE antigen complexes. This suggests that bexosomes can provide the essential transfer mechanism for IgE antigen complexes from B cells to dendritic cells.
Subject(s)
Antigen Presentation/physiology , Antigen-Antibody Complex/immunology , Dendritic Cells/immunology , Exosomes/immunology , Immunoglobulin E/immunology , Animals , Antigen-Antibody Complex/genetics , B-Lymphocytes/cytology , B-Lymphocytes/immunology , Biological Transport, Active/genetics , Biological Transport, Active/immunology , Dendritic Cells/cytology , Exosomes/genetics , Histocompatibility Antigens Class II/genetics , Histocompatibility Antigens Class II/immunology , Immunoglobulin E/genetics , Mice , Mice, Inbred BALB C , Mice, Knockout , Receptors, IgE/genetics , Receptors, IgE/immunology , T-Lymphocytes/cytology , T-Lymphocytes/immunologyABSTRACT
Mast cells and MDSCs are increased by parasitic infection and tumor growth. We previously demonstrated that enhanced MDSC development in ADAM10 transgenic mice yielded resistance to Nb infection and that coculturing MDSCs and mast cells enhanced cytokine production. In the current work, we show that MDSC-mast cell coculture selectively enhances IgE-mediated cytokine secretion among mast cells, without increasing MDSC cytokine production. This effect was independent of cell contact and elicited by Ly6C(+) and Ly6C/G+ MDSC subsets. These interactions were functionally important. MDSC depletion with the FDA-approved drug gemcitabine exacerbated Nb or Trichinella spiralis infection and reduced mast cell-dependent AHR and lung inflammation. Adoptive transfer of MDSC worsened AHR in WT but not mast cell-deficient Wsh/Wsh mice. These data support the hypothesis that MDSCs enhance mast cell inflammatory responses and demonstrate that this interaction can be altered by an existing chemotherapeutic.
