Hello, my name's Lewis Lanier,
I'm Chair Professor of the Department of Microbiology and
Immunology at UCSF Medical School in San Francisco.
Today we're going to be talking about natural killer cells,
which is my favorite cell type that I've worked on for many years.
Why do we have NK cells?
Without them, you'd die of viral infections.
Natural killer cells were first discovered by their ability to kill cancer cells,
but in fact, I think the evolutionary drive was to protect you from viral infections.
It's good fortune that they use the same processes to kill cancers,
so we'll be talking about the ability of NK cells to
recognize virally infected cells, and to eliminate them, today.
The evidence that we have that NK cells are important
comes from experiments of nature, in which there are
rare human beings who have no natural killer cells.
These were discovered back in the 80s,
and these unfortunate people who had no natural killer cells,
although they had normal B- and T-cells,
in fact succumbed to certain viral infections.
The ones that seem to be most important are the herpesviruses.
On this slide you can see a variety of patient case reports,
showing that when you don't have NK cells
you can have severe Epstein-Barr virus (a herpesvirus), severe cytomegalovirus,
and also the other virus NK cells particularly care about is papillomavirus,
which causes warts and cervical cancer in women.
In fact, a few women who've had no natural killer cells have developed cervical cancer.
We also know that NK cells like to take care of viral infections by
experiments in mice, where many years ago it was shown that if you depleted NK cells,
again, NK cells had trouble eliminating certain viral infections.