last updated April 2013
New skills for old cells
A population of immune cells retains the ability to undergo a ‘career change’, giving rise to entirely different immune cell subtypes
Differentiation is usually a one-way street, and most cells that mature to fulfill a particular purpose will retain that function throughout their lives. This is not always the case, however, and new work from a team led by David Tarlinton and Stephen Nutt of the Walter and Eliza Hall Institute of Medical Research in Australia reveals a surprisingly flexible subset of immune cells1.
Follicular helper T (TFH) cells help promote the development of B cells, which secrete antibodies to destroy pathogens and other threats. Relatively little is known about how TFH cells develop, and the researchers genetically engineered a mouse strain expressing a fluorescent marker that made these cells easier to track. Unexpectedly, they determined that TFH cells continue to multiply in adult animals, a behavior typically not seen in fully differentiated cells. Immune system activation stimulated this proliferation, which eventually subsided as the immune response waned.
However, Nutt and Tarlinton observed that TFH cells could become ‘memory T cells’. These recognize and respond rapidly to reappearance of the same immune trigger by giving rise both to various subpopulations of TFH cells and ‘effector’ T cells, which amplify and direct the immune response. This suggests TFH cells can play a more diverse role in immune function than previously anticipated.