and that would be warm though.
Let’s begin at the top.
Let’s take a look at the
protocol for direct Coombs test.
Now, the Coombs test is
indirect and direct.
I’ll give you the indications as to when
you would want to conduct which type
and briefly just
going to identify
or kind of look at the steps
of some of these Coombs tests.
So let’s say you have an
RBC with an IgG antibody.
And right off the bat, I’m going
to go ahead and tell you,
well, we have a state
And, well, for the most part the state
of Georgia tends to remain warm,
but whatever, let's go with
stereotypes in generalities, please.
So it’s warm in Georgia.
The G in IgG if you wish to use
is warm type of autoimmune
Is that clear?
You need to find a way in which
you differentiate warm and cold.
I’m going to keep
so that you know as to what
type we’re dealing with.
Warm is only dealing with IgG.
So here, you have an RBC in your
patient that is stuck with IgG.
We’ll come to that later.
What are we going to do?
We’re going to then identify
the pathologic complex.
This is in the patient.
This complex right here.
So what are we going to use?
We’re going to use an
That’s the Coombs’ reagent.
Make sure you're
familiar with this.
So what is it going to do, do you think?
If you use an anti-IgG antibody,
it’s going to attack or not so much
attack, but really bind the IgGs.
What do you end up forming?
A positive direct Coombs test.
What have you identified with this test?
Oh, I’ve identified an “antigen”
which is the RBC in this case or viewed
as such by the body and the antibody.
Which is which one here?
And what type would that be for you?
Warm or cold?
I haven’t given you any associations.
I haven’t given you any causes.
But what I have given to you,
at this point, is the protocol
that is quick and easy for you to
understand the direct Coombs test, direct.
Now, looking for antibody and/or C3 on
surface of a patient’s RBC is your objective
if you take a look at the
bottom of this page.
So what about the indirect?
How do you use this?
Now, this one, we’re not going to use so
much with our autoimmune hemolytic anemia.
However, this is
an important test.
Well, as I said,
I’ll give you the indications and I’m not
going to go through all the immunology.
However, I’ll give you the basics.
Step 1: You add
test blood group.
Let’s say O.
What does O mean to you?
Universal donor, right?
And the reason that it’s universal
donor is because as you know,
the O type RBC
refers to the fact there are no
antigens on the membrane of that RBC.
Do you remember that
So if there is no
antigens on that RBC,
remember it’s very easy for
you to O, do-nate your RBC
to the recipient that
requires a transfusion.
But this is the problem, right?
Is the O type of RBC able
to receive any blood?
So it’s not a universal recipient
because the O type blood/person/individual
has antibodies for both A and B.
So therefore, it cannot accept any A
type of RBC because, oh my goodness,
you’ll have a transfusion reaction
and the patient is going to
die, transfusion reaction.
Because the O type has antibody
attacking the A RBC from the donor.
But then also has B antibodies.
So if I’m the O type RBC patient
and I’m receiving B type blood,
my antibody is going to
then attack the B type RBC.
Can’t have that either.
That’s a transfusion reaction.
What can I give?
Yes, universal donor.
I’m extremely generous,
but all I do is give, give, give,
but I never receive anything back.
Does that sound like your relationship?
That’s a topic for another day.
But anyhow, add test blood type O RBC
to the test tube to bind to what?
The IgG antibody.
So now what happens?
There you go.
At this point, you have now created
some type of coating of your IgG.
Next, what are you going to do?
You’re going to do step 2, which is adding
that Coombs reagent, which is what again?
It’s an anti-IgG antibody.
You have agglutination.
But then, "So Dr. Raj, this doesn’t
look any different from the direct."
Well, it’s completely different.
I want you to go back
to that first step there.
Do you see those O RBCs there?
Those are not from the patient.
Go back and compare this to direct.
In direct, those RBCs were from the patient
that already had a pre-existing IgG to it.
Is that clear?
Then, what you end up doing is
you get these IgG antibodies
and then they will bind
to the O type test RBCs.
So this is the one that you may want
to spend a little bit more time with
so that your step here,
what are you looking for?
You’re looking for the antibody
in the patient’s serum.
That’s what indirect does.
Indirect is going to then
identify your antibodies.
Coombs test is a?
Read the top.
This is not what we’re going to use
in autoimmune hemolytic anemia.
Why might you ask?
Because in the previous discussion of
direct, in autoimmune hemolytic anemia,
we’re going to find IgG
already bound to the RBC.
And that is what's in the patient.
And what we’re going to do is then confirm
that there is such a complex taking place
and we’ll find agglutination.
If you’re still unclear about
this, well, it’s okay.
For now, you fully
and you keep coming back to
this explanation for indirect.
Then trust me, you’ll
you’ll get it.