It even gets better. The researchers transplanted the white blood cells
into ordinary mice without cancer and found that this made these mice
cancer-resistant as well. Even after these pre-treated mice were
injected with lethal doses of highly aggressive new cancers, they did
not develop the cancer.
This is a real breakthrough. According to Cui “This is the very first
time that this exceptionally aggressive type of cancer was treated
successfully. Never before has this been done with any other therapy."
The original studies were first published in 2003. These studies showed
that the trait can be inherited. The researchers have found that this
genetic trait was passed on to about 40 percent of each generation. Cui
says “The cancer resistance trait so far has been passed to more than
2,000 descendants in 14 generations.”
The goal is to design a treatment for humans. Co-investigator, Mark C.
Willingham, M.D, said this “study shows that you can use this
resistant-cell therapy in mice and that the therapy works. The next step
is to understand the exact way in which it works, and perhaps eventually
design such a therapy for humans."
The transplanted white blood cells include natural killer cells, while
other white blood cells called neutrophils and macrophages that are part
of the body's "innate immune system." This system forms a first line of
host defense against pathogens, such as bacteria. Neutrophils and
macrophages engulf pathogens and destroy them.
Neutrophils cells make up 60% of white blood cells. Both neutrophils
and microphages are created in the bone marrow (microphages are created
from bone marrow), but perform slightly different functions. Neutrophils
cells squeeze through capillary walls to patrol tissue, and are created
in large numbers when an infection occurs. You can see dead neutrophils
as pus. Microphages are larger and live longer than neutrophils. They
are found in organs such as lungs, liver, kidney, spleen, and lymph
nodes. They actually cut up the pathogens to display antigens which are
recognized by lymphocytes.
The original group of cancer-resistant mice, described in Proceedings of
the National Academy of Sciences, successfully fought off a range of
virulent transplanted cancers. The white blood cells have also been
shown to kill endogenous cancers. These cancers spring up naturally in
the body’s own cells. The researchers said “Their activation requires
no prior exposure, but rather depends on a pre-determined mechanism to
recognize specific patterns on the cancer cell surface."
The injected white blood cells do not damage healthy cells. According
to the researchers, if a virulent tumor was planted in a normal mouse's
back, and the transplanted white blood cells were injected into the
mouse's abdomen, the cells still found the cancer without harming normal
cells. The kind of cancer didn't seem to matter.
A single injection of the cancer-resistant macrophages offered long-term
protection for the entire lifespan of the recipient mouse. The
researchers said this was unexpected. Cui says “The potency and
selectivity for cancer cells are so high that, if we learned the
mechanism, it would give us hope that this would work in humans. This
would suggest that cancer cells send out a signal, but normal white
blood cells can't find them."
The next steps include understanding the molecular mechanism. "The real
key is finding the mutation, which is an ongoing investigation in
collaboration with several other laboratories," said Willingham.
Dan Wilson
Best Syndication
Books on Cancer
Keywords and misspellings: microfages
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