Researchers from the Netherlands Cancer Institute have
discovered how cells of the immune system that are present in the
skin offer protection against renewed infections. Their study is
published in the journal Science.
The study was supervised by prof. dr. Ton Schumacher. As an
immunologist, he studies how different parts of the immune system
work. Memory cells are cells from the immune system that are able
to remember what harmful bacteria and viruses look like. This way,
they can quickly come into action when they sense the presence of a
previously encountered intruder. However, a lot of questions about
the exact function of these cells remain unanswered.
Schumacher studied memory cells called CD8+ T cells. Schumacher:
"We have known for some time that these cells remain in the skin
after an infection and offer protection against renewed infections.
But their numbers are small. So how is it possible they can offer
protection to a large area of tissue?"
Schumacher's team has now discovered that these memory cells
protect the skin by sending out an 'alarm signal' when they again
encounter a known intruder. This alarm system, consisting of
so-called cytokines, tells large numbers of skin cells within the
surrounding tissue to switch on a broad variety of anti-bacterial
and anti-viral genes. The genes that become active when this alarm
signal is received are, for instance, genes that can help prevent
viruses from entering cells and thus prevent them from
"One of the surprising things we found, is that the genes that are
switched on offer protection to a broad range of bacteria and
viruses", Schumacher says. So if, for instance, the memory cells
recognize a herpes virus, they will switch on genes in the
surrounding tissue that not only target the herpes virus but also
other, unrelated types of intruders. Thus, this immune response
offers a broad first line of defense against infections.
New insights like these are important for the prevention and
treatment of a number of diseases. Schumacher himself works on the
development of cancer immunotherapy, a new and promising type of
cancer treatment in which the body's own immune system is
stimulated to fight cancer cells. In the same issue of
Science, a study by the research group of dr. David
Masopust from the University of Minnesota appears. Using a slightly
different approach, their work also demonstrates how memory T cells
provide protection by sending out alarm signals. This group aims to
use these new insights for the prevention of venereal diseases such
as infections with herpes virus or HIV.