So now, what we’ll do is we’ll walk
through some of these important drugs
that you want to know that bring
about either cold or warm
type of autoimmune hemolytic anemia.
Let’s begin with penicillin.
In pharmacology, you’ve heard
of penicillin-binding proteins.
When the penicillin binding proteins
are in the membrane and at some point,
in certain populations, this penicillin might
then alter, what that green circle is?
It’s the RBC.
What that P stands for is the
in which in the membrane
it gets altered.
So therefore now, the RBCs
looked at as being an antigen.
Guess what it’s going to do?
It’s going to attract IgG, okay?
What does IgG mean to you?
Warm or cold?
What does IgG mean to you in
terms of hypersensitivity?
It is a type II hypersensitivity.
Once again, what does IgG do to that RBC?
It coats it.
What is that RBC going to look
like and where is it going to go?
It will go to the spleen,
undergo extravascular hemolysis.
On your peripheral blood smear, that RBC
will look like a spherocyte, won't it?
And what about your Coombs test,
which you are going to use?
Direct or indirect?
You’re looking for an
RBC bound to an IgG.
I’m hoping now at this point
you can correctly answer
and say and tell me
that it’s direct.
So take a look at the description
here, type II hypersensitivity,
antibody dependent cellular
Therefore, tell me about the symptoms.
Significant jaundice and pigment stones.
Let us now move on to quinidine.
Now, quinidine is going to
be one of your prototypes
of what’s known as your class
I antiarrhythmic, isn’t it?
So you have quinidine here that the
patient is taking because of arrhythmia
and wants to block off
the sodium channel.
the quinidine has an interesting
effect in which it then brings about
what’s known as an immune
versus a type II hypersensitivity IgG, IgM
you’re going to form an immune complex.
And that will then deposit
on RBC due to quinidine.
So what kind of hypersensitivity is this?
This will be a type III hypersensitivity.
And the big change of understanding now
is the fact that if you
have a type of cold IgM,
then that IgM will
trigger your complement.
And that complement pathway
leads to C3b production
and hence extravascular
Those of you that have learned
it being intravascular and such,
well, be very careful because this is
really not the case anymore clinically.
Methyldopa is what
we’re looking at next.
Please pay attention here.
This is an important clinical scenario.
With methyldopa, who is your patient?
Well, my patient is pregnant
and she has blood pressure of
160/90, first trimester, okay?
So you want to try to tackle
this hypertension, obviously.
I gave you first trimester because
I don’t want there to be any confusion
with preeclampsia here, okay?
So anyhow, you’re trying to treat
the hypertension in a pregnant lady.
She had predisposing
She was already taking ACE
inhibitor for hypertension.
She became pregnant.
Oh my goodness, please remove
her off of the ACE inhibitor
or otherwise, the ACE inhibitor will
kill the fetal kidneys as you know,
it's a teratogen.
But you still have to absolutely
take care of that hypertension,
because if you don’t, then
increase risk of something like
Later on down the road.
So here, you give something called
an alpha-2 agonist centrally acting.
So this is alpha methyldopa.
So by stimulating your alpha 2 receptors
up in the brain, what have you done?
Alpha-2 receptors are located where?
On the presynaptic terminal, isn’t it?
On the presynaptic terminal, you inhibit
the release of your norepinephrine
and therefore, you try to
control that hypertension
and safe from
pregnancy, know that.
In certain populations,
this methyldopa is --
what does Rh mean again?
It’s a D antigen.
This methyldopa in certain
population is going to configure
or shall really disfigure the
Rh antigen in the membrane
to the point where the
RBC becomes absolutely
recognized as an antigen.
Guess who’s going to come in?
So what’s IgG?
What is IgG?
Where does it go?
To the spleen.
type II hypersensitivity.
Do you see as to how the drugs bring about
interesting autoimmune hemolytic anemias?
I have given you three big ones:
Penicillin, methyldopa - IgG
warm, type II hypersensitivity.
Quinidine - IgM, immune complex.
We have all of these really having
extravascular type of picture.