Basophils contribute to T_H2-IgE responses in vivo via IL-4 production and presentation of peptide-MHC class 2 complexes to CD4⁺ T cells

Yoshimoto T. et al. Nat Immunol. 10 (7):706-12. (2009)

Speaker: Yi-ping Lin (林宜平)                                                Time: 14:00~15:00, Sep. 16, 2009

Commentator: Dr. Chun-Keung Yu (余俊強老師)         Place: Room 601

Abstract:

When pathogens invade into our body, naïve CD4⁺Tcell may develop into different subtypes T helper cells and their immune functions [1]. The cellular and molecular mechanisms of the development of Th1 and Th17 cells are well-studied, but how to drive naïve T cells to Th2 cells is still unclear. Previous study has discovered that basophils would activated and recruited into draining lymph node and promoted Th2 cell development when challenge Th2-inducing antigen, but other cells such as dendritic cells recruited to same place the same time [2]. So, the authors want to clarify which cell is the most important cell to initiated Th2 cell development. When mice infected parasite, splenic basophils will expressed MHC class Ⅱ and secreted Th2-type cytokines such as IL-4 and IL-13. In addition, basophils cultured with naïve T cells would lead the development of IL-4-secreting T cells. Surprisingly, basophils form naïve mice also expressed MHC class Ⅱ and promoted Th2 cell development. When binding with IgE complex, basophils will activated and executed it immune function. In this article, Yoshimoto also discovered that antigen-specific IgE complex could enhance the antigen-presenting ability of basophils. If we adoptive transfered IgE complex-pulsed basophils to mice, Th2 cell type cellular immunity will be induced. On the other hand, using antibody to deplete basophils, Th2 type cellular immune response such like IL-4, IL-13 secretions and antigen-specific IgG1, IgE production will diminished. In conclusion, basophils could direct promote naïve T cell into Th2 cells and carry out it immune functions. Basophils is thought to be the major effector cells in allergic inflammation [3], newly discovered also indicate that basophils could initiate Th2 type immune response. This study may be providing a new therapeutic or preventive target to cure or prevent allergic disease.

Reference:

1. Medzhitov R. Recognition of microorganisms and activation of the immune response. Nature 2007. 449(7164):819-26.

2. Sokol L.C. et al. A mechanism for the initiation of allergen-induced T helper type 2 responses. Nat Immunol. 2008. 9(3):310-18.

3. Schroeder J.T. Basophils beyond effector cells of allergic inflammation. Adv Immunol. 2009. 101:123-61.