Consequently, in an attempt to initiate

a self-healing response, we adoptively transferred CCR7+ (B6.WT) DCs into the site of infection of B6.CCR7−/− mice. Surprisingly, instead of healing the lesion, B6.CCR7−/− mice inoculated with B6.WT DCs developed augmented lesions and showed increased immunosuppression compared to control B6.CCR7−/− mice transferred with B6.CCR7−/− DCs or Obeticholic Acid price B6.WT mice with B6.WT DCs. Finally, B6.WT mice injected with B6.CCR7−/− DCs also presented delayed healing of the lesion. These results indicate that CCR7 must be expressed on DCs, as well as peripheral cells, to allow an efficient immune response to L. major. “
“Signal regulatory protein α (SIRPα/CD172a), expressed by myeloid cells including CD11b+ dendritic cells, interacts with ubiquitously expressed CD47 to mediate cell–cell signalling and therefore, may be pivotal in the development of tolerance or immunity. We show that in mice deficient in CD47 (CD47−/−) the cellularity in gut-associated lymphoid tissues is reduced by 50%. In addition, the frequency of CD11b+ CD172a+ dendritic cells is significantly reduced in the gut and mesenteric RO4929097 manufacturer lymph nodes, but not in Peyer’s patches. Activation of ovalbumin (OVA)-specific CD4+ T cells in the mesenteric lymph nodes after feeding OVA is reduced in CD47−/− mice compared with wild-type however, induction of oral tolerance is maintained. The

addition of cholera toxin generated normal serum anti-OVA IgG and IgA titres but resulted in reduced intestinal anti-OVA IgA in CD47−/− mice. Replacing the haematopoietic compartment in CD47−/− mice with wild-type cells restored neither the cellularity in gut-associated lymphoid tissues nor the capacity to produce intestinal anti-OVA IgA

following immunization. This study demonstrates that CD47 signalling is dispensable for oral tolerance induction, whereas the expression of CD47 by non-haematopoietic cells is required for intestinal IgA B-cell 3-mercaptopyruvate sulfurtransferase responses. This suggests that differential CD4 T cell functions control tolerance and enterotoxin-induced IgA immunity in the gut. The intestinal immune system has dual and opposing roles as it must discriminate between harmful substances, to generate an effector response, and benign food antigens, to maintain tolerance. A prominent feature of the intestinal immune system is the generation of IgA-producing plasma cells. Oral immunization with the powerful adjuvant cholera toxin (CT) is dependent on CD4+ T cells to generate antigen-specific IgA.1,2 Dendritic cells (DC) strategically placed beneath intestinal epithelial cells have been shown to be important for the induction of oral tolerance.3 They are essential for immunogenic functions including CD4+ T-cell activation and subsequent generation of antigen-specific antibodies following oral immunization with adjuvants.