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0:00
Hello, my name is Carsten Watzl
and I'm from the
Leibniz Research Centre
in Dortmund in Germany,
and I work with
natural killer cells.
The subject of this presentation
will be the mechanisms
of natural killer cell (NK)
cytotoxicity -
how NK cells kill other cells.
0:20
The best way to introduce this
subject is to actually
show you a video
that we made in our lab.
Here you see tumor cells
that are labeled
in green and NK cells
that are labelled in red.
When we start the video you see
that the NK cells
attach themselves
to the tumor cells and kill
these tumor cells by
direct cellular contact.
They kill the tumor cells
by inducing classical apoptosis,
so you see the
hallmarks of apoptosis,
so the cell shrinking
and the membrane blebbing.
Over the time course
of these three hours,
the NK cells have killed many
of the tumor cells
in this video.
You can see that the
NK cells cytotoxicity
is a rather potent mechanism,
and it's one of the
major functions
of these innate lymphocytes.
The NK cells cytotoxicity is
actually also being
used therapeutically
when we're talking
about CAR T-cell,
so other cancer immunotherapies.
Therefore, it is
important to understand
how NK cells actually
kill tumor cells.
1:22
NK cells are not just killers,
they're actually serial killers,
so they can kill
multiple targets,
but they can only kill
one target at a time.
This is what you see
in these images
that are also taken
from a video that we made.
Again, the NK cell here
is labelled in red
and the tumor cells
are not labeled,
but they will turn
green when they die.
You see in the upper
left picture that
the NK cell makes contact
to tumor cell number one,
and then this cell turns green,
indicative of this cell dying
and being killed by the NK cell.
Then the NK cell makes contact
with tumor cell number two,
kills this one, and so on.
So over the time course
of 12 hours here,
the NK cell has killed
five individual target cells
in a strictly serial fashion.
I'll get to that in a
minute why the NK cells
can only kill one
target at a time.
