Murine basophils express highly in liver and regulate priming of na(i)ve CD4+ T cells to develop into Th2 cells
Objective To compare the levels of murine basophils distribution in different organs and analyze the characteristics of CD4+T cells activation/differentiation regulated by basophils.Methods Firstly,the mononuclear leukocytes were isolated separately from periphery blood,liver,spleen,lung and lymph nodes and the percentages of FceR I+CD49b+ basophils in different organs were investigated.Secondly,liver basophils were purified by immuno-microbead strategy and co-clutured with different cytokines for 24 h.Apoptosis status of basophils was detected by Annexin V straining method.Thirdly,Mice were subcutaneously implanted with a miniosmotic pump containing 5 μg IL-3.At day 7 after implantation,liver mononuclear cells were harvested and the percentages of basophils were analyzed.Finally,Th1/Th2 polarization influenced by basophils orientated cytokines was investigated when naive OT-Ⅱ CD4 T cells were stimulated with spleen dentritic cells and OVA peptides.Results The percentage of murine basophils in mononuclear leukocytes of liver was significantly higher than that of periphery blood,spleen,lung and lymph nodes under physiological condition.Both of in vitro and ex vivo experiments showed that IL-3 played an inhibitory role on apoptosis of basophils.Cytokines secreted by basophils was investigated to induce Th2 polarization and inhibit Th1 response when naive OT-Ⅱ CD4 T cells were co-cultured with spleen dentritic cells and OVA peptides.Conclusion Th2 response was enhanced and Th1 response was down-regulated by murine basophils,which implied that basophils might participate in the construction of liver specific physiological immuno-tolerant microenvironment. 
 
Key words: 
Basophils;  Liver;  Th2 immune response;  Apoptosis