Two free full-text reviews addressing the development and
functions of memory CD4 T cells are available online from the journal
Immunology.
Immunology. 2010 Mar 16. [Epub ahead of print]
The potential of CD4(+) T-cell memory.
McKinstry KK, Strutt TM, Swain SL.
Trudeau Institute, Saranac Lake, NY, USA.
While many aspects of memory T-cell immunobiology have been
characterized, we suggest that we know only a fraction of the effector
functions that CD4 T cells can bring to bear during secondary challenges.
Exploring the full impact of memory CD4 T-cell responses is key to the
development of improved vaccines against many prominent pathogens, including
influenza viruses, and also to a better understanding of the mechanisms of
autoimmunity. Here we discuss factors regulating the generation of memory CD4 T
cells during the activation of naïve cells and how the nature of the transition
from highly activated effector to resting memory upon the resolution of primary
responses might impact memory CD4 T-cell heterogeneity in vivo. We stress that
memory CD4 T cells have unique functional attributes beyond the secretion of T
helper (Th) subset-associated cytokines that can shape highly effective
secondary responses through novel mechanisms. These include the recruitment of
innate inflammatory responses at early phases of secondary responses as well as
the action of enhanced direct effector functions at later phases, in addition
to well-established helper roles for CD8 T-cell and B-cell responses.
Immunology. 2010 Mar 16. [Epub ahead of print]
Memory CD4 T cells: generation, reactivation and
re-assignment.
Macleod MK, Kappler JW, Marrack P.
Howard Hughes Medical Institute and Integrated Department of
Immunology, National Jewish Health, Denver, CO.
Immunological memory is one of the features that define the
adaptive immune response: by generating specific memory cells after infection
or vaccination, the host provides itself with a set of cells and molecules that
can prevent future infections and disease. Despite the obvious importance of
memory cells, memory CD4 T cells are incompletely understood. Here we discuss
recent progress in understanding which activated T cells surmount the barrier
to enter into the memory pool and, once generated, what signals are important
for memory cell survival. There is still, however, little understanding of how
(or even whether) memory CD4 T cells are useful once they have been created; a
surprising thought considering the critical role CD4 T cells play in all
adaptive primary immune responses. In light of this, we will discuss how CD4 T
memory T cells respond to reactivation in vivo and whether they are malleable
to a re-assignment of their effector response.
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