BCl6, a zinc finger transcription factor, contains a N-terminal BTB/POZ domain and C-terminal zinc finger DNA-binding motifs and represses transcription of a wide range of target proteins and microRNAs. BCL6 protein has been reported as a master regulator of B lymphocyte development and growth, and altered BCL6 protein expression was implicated in pathogenesis of diverse human hematologic malignancies, especially in the diffuse large B cell lymphoma (DLBCL). BCL6 is required for the development of T follicular helper T cells (TFH), a helper T cell subset required for the formation of mature and productive GCs. BCL6 has also been shown to play important regulatory roles in macrophages.