Now we're getting to the big boys, okay?
These are the monocytes.
They are the largest of
the white blood cells.
They're up to 3 times the diameter
of a red blood cell, okay?
These are big boys, right?
These are really good size.
So the percentage of white blood
cells is normally 1%-10%.
Now half of them are stored in the spleen,
and when you get hit with an infection,
they get released.
So of the total amount of monocytes
you have in your body,
half of them are ready to go, but
they're stored in your spleen.
That's why patients who have to have
a spleenectomy, a removal of their spleen,
are at an increased risk to
deal with infection.
Because these monocytes are really
important; they're mobile,
they're mortal, and they can
get right into the tissue.
So when you're thinking of monocytes,
they gave you a great picture to look at.
That is like the blob, right? It's really big,
up to 3 times the size of a red blood cell,
and half of them stored in the spleen,
so they respond when you're attacked.
Now, here's what they do.
A function of the monocytes is, first of all,
phagocytosis, wah, wah, wah, wah wah.
So that'll eat up the bacteria.
Now, they also do an antigen
presentation to the T cells,
and we'll talk about those in just a minute.
And they produce cytokines.
So these are like some really bad
bouncers, right? These are really
big cells, and they do some bad stuff. Well,
actually, it's good stuff for your body,
but they can eat the bacteria,
they can present the antigens to
the T cells, and they produce
cytokines, which is an inflammatory mediator.
Okay, so, now we know what they do.
Remember, we talked about that they do
phagocytosis, they take care of
antigens, they produce cytokines.
So it would make sense
that we would have elevated monocytes
and things like chronic inflammation,
the body's under stress.
Cushing's syndrome. Remember, that's an
endocrine disorder when it's the disease,
but when we say Cushing's syndrome,
that means the patient has
received a lot of excess
glucocorticoids as medication,
so that will cause monocytosis.
It might have a viral infection
or even sarcoidosis.
Okay, so we've got another long
list there. You know what to do.
Think through each one of these points.
How can you group these together
in a way that makes sense to you,
so it'll be easier for you to remember?
The 2 most important ones I would remember;
chronic inflammation and stress.
Now monocytopenia, we're
talking about low monocytes,
can be coming from chronic infections.
Okay, now look at the difference in that.
You've got chronic inflammation is elevated,
but chronic infection is going
to be decreased.
Autoim mune disease, leukemia
or AML, aplastic anemia,
and myelotoxic drugs.
So this one is tricky. Just look close
at this and you'll have to look at
your lab values and look
at the patient's history
and their current assessment to figure out
what is the most likely cause of this
change in their monocytes.