Post title at diabetesdaily.com/was:
In the blood stream immune system cells help travel, “stop” at the right location and exit.
In the bloodstream immune system cells help the cancer cells survive and accompany the cancer cells a “run and chase process” to the site where they are to exit the blood vessel.. The immune cells provide substances called chemo-attractants to help the cancer cells stay within their vicinity and not get lost. Remember the blood is flowing fairly fast. And in the blood cancer cells are helped to acquire a shield of platelets that protect them while in the bloodstream; It doesn’t sound like the immune system is out to kill them to me.
Next the cells have to exit as some desired location. Remember cancer metastasizes at precise locations, not at random. So the precise location has to be “primed”, which means immune system cells release substances that cause the cancer cells to be able to roll along the arterial inner wall at the locations in which they want to exit. This is another well-known process.
For the cancer cells to exit the blood stream they have to cross the membrane walls. Here again cells need to move apart to allow the cancer cells to squeeze through. This is tissue permeability and as I mentioned earlier, facilitated by immune system cells.
And sometimes they need to travel through the tissues they enter, which again is facilitated by immune system cells in a process called chemotaxis, again using chemo-attractants.