Bcl6 regulates Th2 type cytokine productions by mast cells activated by FcɛRI/IgE cross-linking

Bcl6-deficient (Bcl6−/−) mice displayed Th2 type inflammation, which caused by abnormality of non-lymphoid cells. However, initiators for the Th2 type inflammation were not clear. In order to elucidate the initiators, we investigated property and function of mast cells derived from Bcl6−/− mice. Mast cells were developed from bone marrow cells cultured with IL-3 (BMMCs). Although the development of BMMCs from Bcl6−/− mice was similar to that from wild-type mice, proliferation of Bcl6−/− BMMCs stimulated with IL-3 was slightly lower than that of wild-type BMMCs. When these BMMCs were stimulated by FcɛRI/IgE cross-linking, Bcl6−/− BMMCs produced Th2 cytokines more than wild-type BMMCs did. Thus, Bcl6−/− mast cells are one of the initiators for Th2 type inflammation in Bcl6−/− mice, and Bcl6 may be a molecular target for Th2 type allergic diseases.