It takes a while for the body to develop and implement a specific immune response. In contrast, the generalized immune response occurs immediately whenever your health is threatened.
Generalized immune response
The immune system responds immediately when your body encounters any threat, such as a virus or injury. In response to such threats, the immune system produces a generalized, non-specific reaction known as inflammation. This response is like an army artillery attack: Shells burst all over, damaging and killing all varieties of bacteria, viruses, and other microorganisms that happen to be in range—including some of the body's own cells.
Key cells involved in this reaction include the white blood cells, macrophages, and neutrophils, which produce powerful destructive chemicals known as free radicals.
In the presence of cancer or the invasion of a dangerous microorganism, your body quickly produces these highly reactive and unstable warrior molecules to take quick action against the enemy germ or physical insult. You can blame free radicals and other elements in the generalized defensive response for the swelling, redness, heat, and pain collectively known as inflammation. Because they are non-specific, free radicals cause the same damage to harmful bacteria as they do to healthy cells, if those healthy cells happen to be in their way.
After the free radicals finish their work, they're turned off, and are converted into non-reactive, harmless molecules. Antioxidant vitamins are essential to this conversion process, which is why you hear a lot about free radicals and the antioxidant vitamins A, C, D, and E.
Specific immune response
As the immune response continues, it becomes more specific. White cells of the blood and immune tissues, called lymphocytes, produce proteins called antibodies that selectively kill the intruding organisms. This leaves other cells of the body undamaged. In addition, your body stores and remembers the "recipe" for the specific antibody concoction created to destroy particular intruders, allowing for a quicker immune response to a similar threat in the future.
Antioxidants and radiation or chemotherapy
Antioxidant vitamins destroy free radicals, and free radicals help destroy cancer cells. Because radiation therapy and certain chemotherapies (such as Adriamycin) work in part by producing free radicals to attack cancer cells, some scientists think the vitamins might reduce this cancer-fighting effect. Many oncologists therefore tell their patients to avoid antioxidant vitamins during these therapies.