TLR-mediated basophil production of IL-4 and IL-13 in human and mouse

It has been previously shown that airway exposure to Toll-like receptor ligands through lipopolysaccharide (LPS)-contaminated house dust or bacterial infections can exacerbate allergic inflammation; however, the underlying mechanism(s) controlling this response have not been fully elucidated. Here we report that basophils are the major source of Th2 cytokines that respond to TLR4 ligands, such as LPS and lipid A, in human PBMC and murine spleen cells. LPS activated human PBMCs to up-regulate mRNAs for not only pro-inflammatory cytokines such as IL-6 and chemokines such as CXCL8 (IL-8), CCL2 (MCP-1), but also Th2 cytokines such as IL-4 and IL13. Among PBMCs, we identified CD123+/BDCA4- basophils as the major source of IL-4 and IL-13 in response to LPS. Even in the absence of IgE, purified human basophils, as well as a basophilic cell line, were directly activated by LPS to produce IL-4 and IL-13. Moreover, LPS-stimulated IL-4 knockin mouse (4get mice) spleens identified the basophils as the major IL-4 producing cells in a TLR4-dependent manner. These results indicate that bacterial LPS may play a role in type-2 immunity through direct activation of basophils to produce IL-4 and IL-13. Keywords: Cell type comparison TLR-mediated production of cytokines in human PBMCs-depleted basophils or basophils are detected.7 independent human PBMCs-depleted basophils samples and 5 independent human basophils samples are included in this series. 2-color analysis was recruited. In each experiment, PBMCs-depleted basophils or basophils are devided to control (Cy5) group and sample (Cy3) group, and sample group was stimulated with LPS, whereas control group was not stumulated. Total RNA was extracted from each of control and sample cells, and amplified. The amplified RNA was labeled with Cy3 or Cy5, and applied to DNA microarray, 3D-Gene.