Activation-induced cytidine deaminase expression in CD4+ T cells is associated with a unique IL-10-producing subset that increases with age

PLoS One. 2011;6(12):e29141. doi: 10.1371/journal.pone.0029141. Epub 2011 Dec 28.


Activation-induced cytidine deaminase (AID), produced by the Aicda gene, is essential for the immunoglobulin gene (Ig) alterations that form immune memory. Using a Cre-mediated genetic system, we unexpectedly found CD4(+) T cells that had expressed Aicda (exAID cells) as well as B cells. ExAID cells increased with age, reaching up to 25% of the CD4(+) and B220(+) cell populations. ExAID B cells remained IgM(+), suggesting that class-switched memory B cells do not accumulate in the spleen. In T cells, AID was expressed in a subset that produced IFN-γ and IL-10 but little IL-4 or IL-17, and showed no evidence of genetic mutation. Interestingly, the endogenous Aicda expression in T cells was enhanced in the absence of B cells, indicating that the process is independent from the germinal center reaction. These results suggest that in addition to its roles in B cells, AID may have previously unappreciated roles in T-cell function or tumorigenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aging / blood*
  • Animals
  • CD4-Positive T-Lymphocytes / enzymology*
  • CD4-Positive T-Lymphocytes / metabolism
  • Cytidine Deaminase / blood*
  • Cytidine Deaminase / genetics
  • Interleukin-10 / biosynthesis*
  • Mice
  • Mice, Inbred C57BL
  • RNA, Messenger / genetics
  • Real-Time Polymerase Chain Reaction


  • RNA, Messenger
  • Interleukin-10
  • AICDA (activation-induced cytidine deaminase)
  • Cytidine Deaminase