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. Author manuscript; available in PMC: 2017 Sep 20.
Published in final edited form as: Immunity. 2016 Sep 20;45(3):471–482. doi: 10.1016/j.immuni.2016.09.001

Figure 3. Clonal dynamics in GCs.

Figure 3

(A) Evolution of clonal diversity in GCs. Each color corresponds to a different clone (a distinct V(D)J rearrangement). Many potentially responsive cells are present in the pre-immune repertoire. Priming involves a competitive bottleneck, which prevents many lower-affinity B cells from entering the GC reaction. Despite this bottleneck, early GCs can still contain tens to hundreds of distinct clones, depending on the antigen used for immunization. Clonal diversity is lost at different rates of in different GCs, so that, by the end of the response to a protein antigen in alum, GCs are distributed across a wide range of clonal diversity. It is not yet known if all GCs would eventually become monoclonal were the response to last indefinitely. (B) Speculative model for the influence of stochastic “noise” (i.e., any factor not directly related to BCR affinity) on GC selection. B cells that fail to gain affinity upon SHM can still be rescued by stochastic factors (e.g., fortuitous encounters with antigen-rich FDC patches or with high-avidity Tfh cells). If the same positive stochastic factors act on a B cell whose affinity increased by SHM, a clonal burst may ensue.