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. 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.
I. Vikstrom, S. Carotta, K. Lüthje, V. Peperzak, P. J. Jost, S. Glaser, M. Busslinger, P. Bouillet, A. Strasser, S. L. Nutt, D. M. Tarlinton, Mcl-1 is essential for germinal center formation and B cell memory. Science 330, 1095–1099 (2010). [Abstract] [Full Text]