New effector functions and regulatory mechanisms of BCL6 in normal and malignant lymphocytes

• BCL6 is important for pre-GC events and for TFH, TFR and NKTFH function in GCs.
• BCL6 is a regulator of T-cell-dependent inflammation and autoimmune responses.
• BCL6 is likely to regulate B and T-cells via cell-specific biochemical mechanisms.
• Dysregulation of BCL6 could contribute to BCL6+ T-cell lymphomas.

The BCL6 oncogenic repressor is a master regulator of humoral immunity and B-cell lymphoma survival. Whereas much research has focused on its regulation and function in germinal center B-cells, its role in other mature lymphoid cell compartments is less clear. A novel role for BCL6 in follicular T helper cell development was recently uncovered. The latest discoveries reveal that BCL6 is also an important regulator of other specialized helper T-cell subsets within germinal centers, pre-germinal center events, and peripheral T-cell effector functions. Here, we review newly discovered roles for BCL6 in lymphocyte subsets residing within and outside of germinal centers, and discuss their implications with respect to the molecular mechanisms of BCL6 regulation and potential links to B and T-cell lymphomas.