12 research outputs found
Epicutaneous Immunization with Protein Antigen in the Presence of TLR4 Ligand Induces TCRαÎČ +
Expression of activation-induced cytidine deaminase enhances the clearance of pneumococcal pneumonia : evidence of a subpopulation of protective anti-pneumococcal B1a cells
We describe a protective early acquired immune response to pneumococcal pneumonia that is mediated by a subset of B1a cells. Mice deficient in B1 cells (xid), or activationâinduced cytidine deaminase (AID (â/â)), or invariant natural killer T (iNKT) cells (Jα18 (â/â)), or interleukinâ13 (ILâ13 (â/â)) had impaired early clearance of pneumococci in the lung, compared with wildâtype mice. In contrast, AID (â/â) mice adoptively transferred with AID (+/+) B1a cells, significantly cleared bacteria from the lungs as early as 3 days post infection. We show that this early bacterial clearance corresponds to an allergic contact sensitivityâlike cutaneous response, probably due to a subpopulation of initiating B1a cells. In the pneumonia model, these B1a cells were found to secrete higher affinity antigenâspecific IgM. In addition, as in contact sensitivity, iNKT cells were required for the antiâpneumococcal B1a cell initiating response, probably through early production of ILâ13, given that ILâ13 (â/â) mice also failed to clear infection. Our study is the first to demonstrate the importance of AID in generating an appropriate B1a cell response to pathogenic bacteria. Given the antibody affinity and pneumonia resistance data, natural IgM produced by conventional B1a cells are not responsible for pneumonia clearance compared with the AIDâdependent subset
Epicutaneous immunization with ovalbumin and CpG induces TH1/TH17 cytokines, which regulate IgE and IgG2a production
Epicutaneous Tolerance Induction to a Bystander Antigen Abrogates Colitis and Ileitis in Mice
Natural killer cell memory in infection, inflammation and cancer
Immunological memory can be defined as a quantitatively and qualitatively enhanced immune response upon rechallenge. For natural killer (NK) cells, two main types of memory exist. First, similarly to T cells and B cells, NK cells can exert immunological memory after encounters with stimuli such as haptens or viruses, resulting in the generation of antigen-specific memory NK cells. Second, NK cells can remember inflammatory cytokine milieus that imprint long-lasting non-antigen-specific NK cell effector function. The basic concepts derived from studying NK cell memory provide new insights about innate immunity and could lead to novel strategies to improve treatments for infectious diseases and cancer