Inflammation

Inflammation is a pathology that many people face normally. The symptoms are common and known: redness, swelling, hot, etc. But what is inflammation?

When injury occurs, immune systems cells need to be in the location to prevent invasion of pathogens. Circulation increases to the area to allow immune cells to enter to location and they get to work to fix the damage. This is inflammation. Cancer in a patient can also stimulate the immune system in similar ways. Immune cells traffic over to the cancer and have interactions.

It was believed in the beginning that immune cells were only tumor-antagonizing. Since immune system cells kill invaders, it was thought that they only do the same to cancer. But research shows that the immune system can have both tumor-antagonizing and tumor-promoting effects. Here are some of the key immune system players in inflammation.

Cytotoxic T lympthocytes (CTL) and Natural killer cells (NK). These cells help the tumor-antagonizing effects on cancer with their ability to directly kill cancer cells.

Macrophages. While macrophages have a part in killing and eating cancer cells, they also have tumor promoting roles. Macrophages produce a protein called HIF-1, or hypoxia (low oxygen) inducible factor. In the low oxygen environment of tumors, HIF-1 is activated in macrophages. This activation leads to to other molecules being activated, such as VEGF. VEGF promotes the formation of blood vessels to connect the tumor to vasculature, which can give the tumor more fuel for growth.

Myeloid derived suppressor cells (MDSC). MDSCs are immune cells that function to suppress the activity of NK and CTLs. Since NK and CTLs are tumor antagonizing, MDSCs are considered to be tumor promoting.

Source: https://hypoxygen.com/blog/123-hypoxia-and-the-hallmarks-of-cancer-inflammation-and-immunity.html
Immunity. 2014 Oct 16; 41(4): 518–528.
Nature Reviews Cancer 12, 298-306