viral activation of T-lymphocytes

Tyson tyson at canada.com
Sun Nov 7 01:52:48 EST 1999


that's correct, epithelial cells can express MHC

Philip Fung <phfung at NOSPAM4ME!owlnet.rice.edu> wrote in message
news:7vvlbb$n18$1 at joe.rice.edu...
| I may be wrong on this one, but I'm pretty sure that all (or nearly all)
| nucleated
| cells have MHC Is, right? and MHC Is present peptides processed in the
| cytosol, right? That's how the viral peptides are presented on MHC Is...
the
| virus infects the cells, and starts transcribing its proteins. Then the
cell,
| by way
| of the proteasome, processes those cyosolic proteins. Any cell infected by
a
| virus can present viral antigenic peptides on its MHC Is. As long as there
is a
|
| T-cell to be activated by it, it can happen. at least according to my
textbook
| (Kuby, 1997)
|
| Activation doesn't have to happen in the lymphoid tissue, either. However,
most
|
| of it does happen there, at least from what I understand, but there are T
cells
| in
| the bloodstream that can come in contact with the MHC Is of other cells in
the
| body. But you're right. epithelial viral infections, like HPV, often do
not
| elicit as
| large of an immune response because it is relatively difficult to access,
in
| terms
| of the lymphocytes abilities to "reach" MHCs in those areas.
|
| One side note, there are also certain superantigens (certain proteins
produced
| by
| certain viruses and bacteria) which serve to activate T-cells w/o an
antigenic
| peptide in Class II MHCs, but that's something else... But a virus can
cause
| T-cell activation by that route.
|
| Phil
|
| Morten Lindow wrote:
|
| > I have got a question about the activation of naive T-cells by viral
| > antigens.
| >
| > According to my textbook (Janeway-Travers) activation of CD8+ T-cells
| > require recognition of MHC class I loaded with viral antigen and
| > costimulation through CD28 by B7.1 or B7.2 on an APC. All this takes
place
| > in lymphoid tissue.
| >
| > The question is: What happens if a virus doesn't infect APCs? Say it is
| > specific for epithelial cells.  How does viral peptides  then end up on
| > class I molecules on APCs?  I figure that APCs could phagocytise free
viral
| > particles, but wouldn't that result in presentation on class II MHCs?
| >
| > Is there a flaw in my understanding? Any ideas and comments would be
very
| > welcome.
| >
| > Regards,
| >
| > Morten Lindow
| > Copenhagen, Denmark
|
| --
| +++++++++++++++++++++++++++++++++++++++++++++
| Philip Fung
| Sid Richardson College
| Rice University   GO OWLS!
| +++++++++++++++++++++++++++++++++++++++++++++
| Let us so live that when we come to die even the undertaker will be sorry.
| - Mark Twain
|
|






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