Control of isotype switching by T cells and cytokines.

Since the discovery that isotype switching is mediated by a somatic rearrangement event, progress in the field of isotype switching has come a long way: switch factor activity for several T-cell-derived cytokines has been discovered. The mechanism of action of these switch factors seems to be related to their ability to increase or decrease the transcriptional activation of particular switch regions. We have, however, yet to fully understand this important step in isotype regulation.