Back to some of my old “favorite” cells, the IL-4-producing CD4 T cells :]
It is well established that IL-4-producing CD4 T cells can be categorized into two subsets.
1) Some are present in lymphoid tissues within germinal centres (GC ) structures. These cells are called follicular helper T cells (TFh cells) and are required for selection of B cells in GC, to switch Ig class, and the induction of the selected B cells into plasma cells, memory B cells and centroblasts.
2) Others CD4 T cells are localized in musocal tissues (lung for instance) and often co-produced IL-4 and IL-13. These cells are called T helper 2 (Th2 cells) and are required during protective responses to Helminth infection while under some circumstances can also be responsible to allergic airways inflammation.
Therefore, it is questionable whether similar mechanisms regulate the production of a given cytokine (here IL-4) within the same cell type (here CD4 T cells) in different location?
Two papers back to back in Immunity (2012- Vol6- N2) from Ansel and Kubo and colleagues demonstrate that Th2 and TFh cells differ in their requirement for specific genomic DNA regions in the IL-4 locus.
They both show that TFh cells are more dependent on the CNS2 in the Il4 locus than Th2 cells.
These are the first clear demonstration that a TFh cell is NOT a Th2 cell; and vice versa! Thus, if you want to read more here are the links:
P. Vijayanand,…, M. Ansel. Immunity. 2012; 36(2):175-187
Y. Harada, …, M. Kubo. Immunity. 2012; 36(2):188-200.