00:01
So, final kind of summary.
00:05
T cell, yeah,
immune responses in
general are protective.
00:09
They're good for us,
they protect us from microorganisms,
they protect us from tumours.
00:15
However,
immune response can be
harmful in a number of ways.
00:21
One, you are eliciting,
particularly in a
DTH type response,
delayed type hypersensitivity,
a lot of antigen
nonspecific mediators
and you're activating a
whole bunch of macrophages,
which don't have any
particular antigen specificity.
00:36
So there's a lot
of potential damage
from those guys that don't
have antigen specificity.
00:43
You can have a lot of
innocent bystander damage.
00:45
So reactive oxygen species,
proteases being
elaborated will cause
more damage than just the
original insult or infection.
00:56
Foreign bodies,
as we just talked about,
will elicit initially
an innate response
that can be deleterious
because it causes
local inflammation,
because it causes local scarring
and will ultimately in
many cases also in gender
a an effector T cell response.
01:18
IgE mediated responses in general
are going to be allergies,
anaphylaxis,
asthma, which will be
deleterious to the host.
01:29
Again, were intended to be helpful
in dealing with worm infections.
01:34
Cross reactive anitgens.
01:35
So we talked about, for example,
in rheumatic heart disease,
where that streptococcal
bacteria elicits an antibody
that happens to
react with hosts.
01:46
So again, the immune system
is just doing its job,
it's doing what
it's supposed to do.
01:50
But sometimes you
make antibodies,
or T cell recognition
that crosses over just a
little bit in response to self.
02:00
You can have
intracellular infections.
02:01
And again, the only way
that we can deal effectively
with intracellular infections
is to destroy the infected cell.
02:08
So remember the case of hepatitis
B where the viruses in there
and once we recognise
that cell is infected,
we kill it, because that's the only
way to clear the viral infection.
02:19
Autoimmunity,
special circumstance
where you have loss of
tolerance to self antigens,
will clearly bring into play
all of these various components, T
cells, B cells, macrophages, neutrophils.
02:34
And then finally
allograft rejection.
02:36
So we haven't really talked
about allograft rejection.
02:39
If you want to,
contact me,
we'll talk about allograft rejection
because that's what
I do my research on.
02:45
But when we put in
a foreign graft,
a new heart, a new liver,
a new kidney, new lungs,
what we're also doing is
putting in foreign MHC,
major histocompatibility
complex.
02:56
And now, the recipient,
the person who's
getting the donor organ,
sees this brand new heart,
liver, lung, whatever,
as one big microbe,
and brings to bear all
of the immune system
to try to get rid of it.
03:13
And that's all our
graft rejection is.
03:15
Again, predictable consequences
of activating the immune system.
03:20
So with that, we have gone through a
fairly significant amount of immunology.
03:25
Hopefully, we've made it
really attractive to you
but also kind of illustrated
how this causes disease.
03:33
And hopefully you will
take this way with you
and enjoy thinking
about mechanisms.