Electron micrograph of cross-presenting human skin DCs, isolated based
in part on their expression of high levels of the cell-surface marker CD141.
Recently uncovered human counterparts to a subset of mouse immune cells
may enable better vaccination strategies
Mice have made an immeasurable
contribution to medicine and our overall understanding of human disease. This
animal model is not without its limitations, however, and scientists are
continually learning about important ways in which mouse and human biology
differ.
Both human and murine immune
systems, for example, function in a similar fashion, but individual subtypes of
human immune cells often display characteristics unlike those of their mouse
counterparts. These differences make it difficult to directly translate mouse
data into medically meaningful results. By identifying parallels between a
crucial class of immune cells in mice and humans, a team led by Florent Ginhoux
of the A*STAR Singapore Immunology Network has obtained valuable insights that
should accelerate this translation1.
Cells known as dendritic cells
(DCs) are at the immune frontline, capturing pathogen-derived antigens and
training other immune cells known as cytotoxic T cells to recognize them via a
process called ‘cross-presentation’. “This is very important, as it is the only
way DCs can present tumor-derived antigens or viral antigens without being a
tumor cell or directly infected by a virus,” explains Ginhoux. “And, it has
important implications for vaccine design, where you want to get a good
cytotoxic T cell response.”
A subset of DCs found within the
murine skin plays a particularly prominent role in this process, but equivalent
cells have not yet been identified in humans. DC subsets that look similar but
function differently from each other can be distinguished via distinct
combinations of surface proteins that act as a ‘name tag’. Through careful
analysis, Ginhoux and his co-workers isolated and characterized a population of
skin cells that express high levels of the protein CD141 (see image), which
effectively tags this human DC subset.
The researchers determined that
these skin DCs indeed possess the cellular machinery needed for
cross-presentation. Ginhoux believes they should offer a useful tool for
training the immune system to fight disease. “Now that we know that this
population exists, our aim is to understand how to mobilize it, activate it and
to target it with adjuvants and antigens relevant for vaccination,” he says. In
the process of characterizing these cells, the researchers also succeeded in
profiling the expression of various ‘name tag’ proteins. From these profiles,
they can draw parallels between equivalent DC subsets in mice and humans,
building a valuable informational resource for future research. “This will
allow clear inferences to be made between mice and humans,” says Ginhoux.
The A*STAR-affiliated researchers
contributing to this research are from the Singapore Immunology Network and
theSingapore Institute for Clinical
Sciences
References
- Haniffa, M., Shin, A., Bigley, V., McGovern, N.,
Teo, P. et al. Human tissues contain CD141hi cross-presenting
dendritic cells with functional homology to mouse CD103+ nonlymphoid
dendritic cells. Immunity 37, 60–73 (2012).
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