Asymmetric B Cell Division in the Germinal Center Reaction

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Abstract
Stochastic or Asymmetric Fate Determination?: During an adaptive immune response, B lymphocytes rapidly divide and differentiate into effector cell populations, including antibody-secreting plasmablasts and memory B cells. Many also change the class of antibody they secrete, through a process called isotype switching. During this process, some cells die. Whether cells acquire these different fates in a stochastic or programmed manner, however, is unclear. Duffy et al. (p. 338 , published online 5 January) used single-cell tracking to determine the times to division, differentiation into a plasmablast, isotype switching, and death of stimulated B lymphocytes. Statistical analysis and mathematical modeling revealed that these cell-fate decisions appear to be the result of random clocks: Which clock went off first (division, differentiation, or death), determined the fate of the cell. Barnett et al. (p. 342 , published online 15 December) sought to determine whether asymmetrical cell division, which is thought to contribute to effector cell-fate decisions in T cells, may be at work in B lymphocytes. Indeed, factors important for the initiation and maintenance of germinal center B lymphocyte identity, along with an ancestral polarity protein, were asymmetrically distributed and maintained their asymmetry during cell division.
Funding Information
  • U.S. Department of Defense (W81WWXWH1010185, W81WWXWH1010185)
  • U.S. Department of Veterans Affairs (BX000435, BX000435)
  • National Institutes of Health (AI042370, AI076458, T32GM07229, T32HD007516, 3T32GM007170-36S1, T32AI055428, AI065644, AI042370, AI076458, T32GM07229, T32HD007516, 3T32GM007170-36S1, T32AI055428, AI065644)