Now when you talk about lymphocytes,
we have three types:
T cells, B cells, and NK cells.
So the T cells and the B cells are
named from where they come.
NK just means natural killer
cells, so they're pretty cool.
So T cells mature in the thymus.
So make sure you circle the "T"
and circle the "T" in thymus
and underline it, so it's easy
for you to remember.
Now, these guys are helper cells.
They're the servants.
They're the ones who really get
in there and get the job done.
They're helper cells because
they help other cells mature,
activate, and function.
So that's the first type of T cell.
There's T helper cells.
Next, there's T cytotoxic cells.
Now, these guys
destroy cells that are infected with
viruses. That's pretty cool.
So T cells come from the thymus.
There's T helper cells that help
other cells be all they can be.
There's cytotoxic T cells that destroy cells
if they've been infected with a virus.
Remember, viruses come in
and take over cells.
And then there's memory cells
because they remember antigens
from past infections.
This is what's really cool.
That's what helps you fight off infection. If
you've been infected with something before,
these T cells remember and they'll
help you deal with it.
Now the B cells are formed in the bone, okay,
so that's really an easy way
to remember things.
T cells come from the thymus, B
cells come from the bone.
Now, in your plasma, they produce large
amounts of antibodies, which is awesome
because that can deliver it all the
way around through the body.
They also are B memory cells, so
they remember past infections, too.
The last group are the natural killer cells.
Now, they're kind of similar
to the cytotoxic T cells,
but they kill virus-infected
cells and tumor cells.
Okay, let that sink in.
Did you know that your body, your immune
system, can actually kill cancer cells?
Yeah. They do it all the time. So when
we're thinking about lymphocytes.
Let's back it up. They do some amazing things.
When it comes to killing cells,
natural killers can kill
virus-infected cells and tumor cells.
Cytotoxic T cells destroy cells that
are infected with viruses.
So there's something we can
chunk and put together.
That which ones have memory? The B
cells and the T cells have memory.
Other than that, T cells are helpers,
and the B cells produce large amounts
of antibodies in the plasma.
So that's kind of looking at the 3
different types of lymphocytes.
So we've got T, B, and NK, natural killer cells.
They're usually about 15%-41%
of your total white blood cells.
Now you get your lab work back, you
notice your white cell counts are up,
and now you look at specifically
the lymphocytes are up,
so that could be a sign of
a viral infection.
The neutrophils respond initially
to bacterial more.
So if the neutrophils are up, that's
probably a bacterial infection.
But if the lymphocytes are up,
that's probably a viral infection.
So that's one way
you can tell the difference
just from the CBC test.
Okay, the leukemias can also
cause an increase in lymphocytosis
and adrenal insufficiency.
So again, you're looking at all your
patient's assessment, all their information,
and if you notice -- you're seeing
signs of adrenal insufficiency
and they have lymphocytosis, that
helps you make a better diagnosis.
Okay, now lymphocytopenia is
going to be what you see
in a person who is HIV positive.
That means you have Human Immunodeficiency
Virus present in your bloodstream,
and that destroys the T cells;
the CD4 T cells, specifically.
Now the difference between HIV
and full-blown AIDS is once
the CD4 T cell level gets <200,
and they have an opportunistic infection,
then that means they are in full-blown AIDS.
So, HIV means the virus is present,
but AIDS means it has destroyed so many
of the T cells that the CD4 T cell count
But for now, remember a low lymphocyte
count or lymphocytopenia
one reason could be because
the patient has HIV.
Also, if their bone marrow is failing,
for whatever reason, or aplastic anemia,
you'll see low lymphocytes.
Again, comes back up,
This is lupus. SLE is systemic
RA stands for rheumatoid arthritis.
Then comes up with chemotherapy
Okay. So we talked about HIV.
Does it make sense why bone marrow
failure would give you low lymphocytes?
Right. Bone marrow failure is going
to give you low blood cells, period.
Excessive glucocorticoids, we've
discussed that in previous issues,
and see how many times that comes up.
My best recommendation would be for you
to make 1 chart and flip this around
backwards. It's a great strategy.
Pick something like immunosuppression,
and then list all of the different
that are caused by immunosuppression.
Look at excessive glucocorticoids
and list all those again.
Making your own chart will really help you
supercharge your studying
habits and your retention.
So go back through the slides
when you have some time,
after you're done watching the video,
and make a new and different chart.
That way, you're showing your brain
how to look at this information
from a different perspective.
I promise you, the time you
invest will pay off big.