Bcl-6 Uncouples B Lymphocyte Proliferation from Differentiation
The effective stimulation of lymphocytes by antigen has three potential outcomes for antigen-specific clones, their replication leading to net expansion of cell numbers, their differentiation into effector cells and their differentiation into memory cells. The coordination of these cellular responses is important because, as in other cellular systems, differentiation to the effector stage of development may be associated with an inability to replicate further. For B lymphocytes, terminal differentiation is coupled to cessation of mitosis since non-transformed plasma cells cannot re-enter the cell cycle; it is not clear if terminally differentiated effector T cells have a similar limitation. Therefore, in the immune sytem where the number of antigen-specific clones in a naïve individual is low, premature terminal differentiation occurring before sufficient cellular replication has been achieved would limit the effectiveness of an immune response. Yet, the need for clonal expansion must be appropriately balanced with the obvious benefits of early control and elimination of the infectious process by differentiated lymphocytes. Finally, control of effector cell differentiation and function in the immune system may protect the individual from autoimmune or allergic disease.
KeywordsZinc Finger Germinal Center Terminal Differentiation Raji Cell Promyelocytic Leukemia Zinc Finger
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