Mcl-1 is Essential for Germinal Center Formation and B Cell Memory

The humoral immune response, which comprises antibodies secreted by B lymphocytes, is critical for protection against pathogens. In response to infection, B lymphocytes proliferate and differentiate into antibody-producing effector cells. After an infection clears, a small number of cells persist as memory B cells; however, the survival signals that regulate effector and memory B lymphocyte generation are not well understood. To probe this question, Vikstrom et al. (p. [1095][1], published online 7 October) deleted prosurvival genes in activated, antigen-specific B cells during a T lymphocyte–dependent immune response in mice. They found that a specific programmed cell death inhibitor, known as Mcl1, was required for the formation of germinal-center B cells (an effector cell population) and memory B cells but not for their maintenance. Dysregulation of the B cell responses mediated by Mcl1 may be a trigger for lymphomagenesis. [1]: /lookup/doi/10.1126/science.1191793