I confess to some naivete (hah). But glad to see that the signal 2 has
been mentioned at last. If you consider the response to danger, it would
not be surprising if some accidental bystander triggering of potentially
autoimmune cells would occur. I agree that this event may be rare. One
should also consider that downregulatory mechanisms (for example, IL10
secretion in the response to LPS) almost immediately are triggered in
response to inflammation, and that there are numerous ways in which the
response has to be controlled and turned off before the self is damaged.
My point is that possible such intereractions occur but are contained,
along with control and containment of the beneficial (if not taken to
extremes) response to a pathogen. In addition it should be pointed out
that most of us have autoantibodies (to CD4, for example) to a number of
self antigens which do not appear to be pathogenic at all.
