Plasmacytoid
dendritic cells (look a lot like plasma B cells but express different proteins
on their cell surface) are important interferon-producers in the presence of
viral RNA or DNA (an interferon is a cytokine, or a signaling protein released
in response to a pathogens). pDCs are
important in linking the innate (nonspecific) and adaptive (specific) immune
response through increasing the function of natural killer and T cells,
respectfully.
Much is
still unknown about pDC function, though.
As discussed in Li et al.,
there is a debate on whether pDCs inhibit HIV/SIV replication or instead
promote chronic immune activations and disease.
In other words, what is the role of pDCs in lentiviral (long incubation
period) infections? Using SIV (Simian immunodeficiency viruses)-infected
rhesus monkeys, Li et al. tried
to determine the systematic distribution of pDCs using a cell counting/sorting
mechanism called flow cytometry. They
also looked their cytokine expression and affect on T cell activation upon
infection.
In their study, Li et al. found that chronic SIV infection redistributed pDCs from the
blood and lymphoid organs to the gut and gut associated draining lymph nodes,
described as “gut-homing.” Also, infection
caused pDCs to secrete an increase in specific proteins (ex. TNF-alpha and
INF-alpha cytokines) used to communicate/activate with other immune cells. These two results are consistent with prolonged
immune activity that is linked to progressive diseases, like cancer, cardiovascular
problems, and liver and kidney failure, as seen in HIV infections.
So why
should you care about this? Well, by
better understanding how our immune system responds to pathogens, both in
positive and negative ways, we are more capable to treat and even prevent
complex diseases like HIV, where many develop problems that arise from the
elevated level of the immune response rather than the virus itself.
Primary
article:
Li, H., Gillis, R., Johnson, R. & Reeves, R.
(2013). Multi-functional plasmacytoid
dendritic cells redistribute to gut tissues during simian immunodeficiency
virus infection. Immunology, 140(2), 224-9.
doi:http://onlinelibrary.wiley.com/doi/10.1111/imm.12132/abstract;jsessionid=1689DA62A55C5ADC438859F2190D8475.f02t02
pDC
background:
Colonna, M., Trinchieri, G. & Liu, Y. (2004). Plasmacytoid
dendritic cells in immunity. Nat Immunol, 5(12), 1219-26. doi: http://dx.doi.org/10.1038/ni1141
pDC image:
http://www.s-ibm.org/data/pathology_data/#1
Adorable rhesus monkey image:
http://animals.nationalgeographic.com/animals/mammals/rhesus-monkey/
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