What is the immune system?

What is the immune system?

Well, the immune system is part
of the human body

that monitors and surveils

for anything abnormal going on
that shouldn't be there.

I think the primary role of
the immune system

is to recognize and eliminate infections.

So the immune system gets revved up

when it's exposed to certain pathogens,

such as might be carried on viruses
or bacteria,

and help to eliminate those organisms

in order to help the host survive.

So without an immune system,

you can't really survive for very long
because opportunistic infections

would set in and cause a person to die
relatively quickly.

So that's what we saw with the AIDS
epidemic in particular

was that the HIV virus attacked
the bodies, an important component

of the body's immune system, the T cells,
and left patients very vulnerable to very

unusual types of infections

that would normally never cause a problem
in the healthy individual hosts

such as pneumocystis carinii pneumonia
and other types of infections.

The immune system is also very important
in monitoring for cancer,

so the immune system develops mechanisms

for recognizing cancer cells
that have developed

and help to eliminate them
before they become a problem.

So patients with compromised
immune systems who have deficiencies in T

cells or B cells
or other components of the immune system

are more predisposed
to various types of cancers.

So the immune system
also has an important role in monitoring

and recognizing cancer
as well as infections.

So the immune system is

our bodies innate system to help

fight infection, whether it's fungal
infection, bacterial infection.

We have, antibodies that the body develops

that can help fight,
particular infections.

The immune system is the one
that is the most

commonly affected
as in the setting of blood cancers, as

many times the

acute leukemia affects all the bone
marrow cells.

So the myeloid cells typically
are the cells that help will help

eventually mature into the red blood
cells, white blood cells and platelets.

And that factory is what helps
the immune system build.

How does AML affect the immune system?

Well,
the immune system is a complex organ,

if you want within the human body
consisting of different components

from the T cells to the neutrophils

macrophages
in activating T cell immune responses.

It's known, though, that

acute myeloid leukemia that progresses
within the bone marrow and within the bone

marrow leads to immune suppression

by simply reducing
the number of white cells and associated

with that a low number of neutrophils,
which then explains why patients

get infectious complications, why
they get neutropenic fevers and so forth.

So the rationale to treat AML effectively
with chemotherapy and subsequent

allogeneic stem cell transplant
is to prevent the immune suppression

induced by the by the majority of leukemia
cells in the bone marrow

by eliminating them and replace
with healthy stem cells that produce

healthy neutrophils,
healthy key lymphocytes,

and therefore renew the immune system
overall.

This then is a donor derived
immune system, not your own anymore.

And that's the complexity of the
allogeneic stem cell transplantation,

which also now the theory behind

allo transplant for AML or other diseases
is not necessarily to kill the last tumor

cell, but induce a new immune system
that allows to recognize

the last tumor cell in the bone marrow
or anywhere in the body.

So the rationale behind transplant
has completely changed over the last years

with with this approach and the new way
of thinking about why we are doing it.