You appear to have the main theme of what I was trying to say. When talking
about T-cell apoptosis absence in the synovial fluid I was reffering to the
apoptotic process in the absence of a co-stimulatory signal (i.e. B7 etc.). A
few journal reports in animal models of arthritis have shown clear evidence of
apoptosis of the T-cells without the co-stimulatory signal, shown with ex vivo
cultures of synovial cells. No evidence of apoptosis occured in the synovial
fluid, so the only difference to the cells was in thier imediate environment
(i.e. whether or not they were within the synovial fluid or not). Outwith the
synovial fluid apoptosis occured very quicky, both in in vitro cultures and in
other areas of the same animal. Hence, it would appear that some factor within
the synovial fluid must prevent this apoptosis process occuring. Which, I
thought to be a relatively rare state of affairs, thus making the synovial fluid
a special case in immune systems.
As I am still only a student, I am on unfamiliar teritory, however some of the
reports I have read, appeared to suggest that the activation of the naive
T-cells only occurs in vivo within the lymphatics. So what I was trying to say
is this, No obvious reason occurs that the autoantigen of RA should leave the
confines of the joint, hence how could they activate naive T-cells to become
activated unless this process occured within the joint.
In terms of the CNS system that you reffered to, I was unaware that only
activated T-cells cross the blood brain barrier, this being the case kind of
kills my idea. Thus the idea of molecular mimicry gains weight if the antigens
could be found to be restricted to the CNS system (or the joint system) by the
blood brain barrier (or a synovial membrane barrier of some kind).
Techniques such as ELISA for the CNS antigen in the lymphatic system may be able
to indicate that the antigens indeed do not leave the CNS.
I'm sorry if I never made myself clearer in my last response. I hope this clears
up your queries on my statements.
I was merly trying to understand a bit deeper than what I'm currently being
taught at University, where many questions have been left unanswered by the
Lecturers. I like to try and come up with novel ideas, unfortunately most of
them are a bit silly.
Andrew
