The Effect of Boosting on CD8+ T Cell Differentiation and Memory
After infection, CD8+ effector T cells undergo contraction leaving a small antigen-specific T cell memory pool poised for recall. These researchers have recently found that sequential immunization with heterologous vectors induces a permanent increase in CD44hi CD62Llo CD8+ memory T cells due to a profound decrease in contraction (Nature 457,196-199). Why do CD8+ T cells that undergo multiple stimulations have decreased contraction post infection? The researchers found that they exhibit unique memory commitment markers, division rates, and maintenance requirements in comparison to primary effectors. Furthermore, their unique program is not solely intrinsic as the immune environment plays a pivotal role in regulating their transcriptional profile and maintenance. Knowing the mechanism(s) of superior CD8+ T cell establishment and maintenance may be key to developing an effective CTL vaccine.