You know the immune system is a collection of reactions and responses in our body that protects us from infections and disease. But can it protect us from cancer?

There are two types of immune responses: innate and acquired. Everyone has innate immune protection, which is always prepared to defend us.

Acquired (or adaptive) immune protection occurs when the immune system learns to recognize something as harmful (for example, a virus) from being exposed to it. The next time it encounters this danger, it launches an attack against it. This is similar to how vaccines work.

Within the immune system, four types of cells directly fight invaders. One of these is cytotoxic T lymphocytes (CTLs), which are white blood cells. They are part of the adaptive immune response. CTLs recognize specific patterns of molecules that are not normal. In the case of cancer, CTLs recognize specific markers on the surface of tumor cells and launch an attack against those cells.

Boosting the Immune System to Fight Cancer

Immune surveillance theory suggests that potential cancer cells arise frequently; however, the immune system recognizes they are not normal, healthy cells and usually destroys them immediately. The immune system also mounts attacks against established cancers, although it's not always successful.

In lab studies, some—but not all—mice exposed to low doses of a carcinogen developed rapidly growing tumors, leaving scientists to question whether the cancer-free group might be more innately immune to cancer. They also found that mice with compromised immune systems were more likely to spontaneously develop tumors and were more susceptible to developing tumors when exposed to a carcinogen.

Similarly, humans with depressed immune systems have an elevated incidence of certain cancers, while cancer patients whose tumors contain a large number of CTLs and other immune system cells cope with their disease more effectively.

Perhaps, therefore, visible cancer represents a rare failure of a system that has been successfully eliminating tumor cells throughout an individual's life.

The immune system produces limited quantities of CTLs at a time and they are short lived, limiting their usefulness in fighting tumors. However, scientists have discovered they can "mass produce" CTLs in the lab, which may make them helpful in potential cancer treatments. One study, for example, found a type of CTL that recognizes a certain marker on melanoma cancer cells. It might be possible at some point to use CTLs to transfer cancer resistance to treat or prevent malignancies.

A promising reason to keep your immune system healthy. At the very least, building a stronger immune system will help you resist fewer colds come winter.

Rajiv V. Datta, MD, FRCS, FACS, FICS, reviewed this article.




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