The immune system contains a set of specialised cells and soluble molecules called cytokines. These cytokines interact with each other to respond to invading pathogens such as bacteria, viruses, parasites and fungi, as well as defend against tissue changes induced by cancer-causing viruses or abnormal changes to a healthy cell.
Even more importantly, a healthy immune system controls unwanted reactivity to our own healthy tissues (i.e. the prevention of autoimmune conditions). The optimal, balanced functioning of the immune system is therefore a critical factor for health preservation.
Arms of immunity
To better understand the manner in which the immune system functions, we often describe the two arms of immunity: innate (natural) versus specific (acquired). The innate immunity is non-specific but reacts very quickly. The acquired immunity, on the other hand, is highly specific and slower to respond, but lasts a lifetime:
The role of acquired immunity
The most important cells of the adaptive/acquired immune system are the T cells. There are various types of T cells, each with very distinct functions:
• The TH1 cells release cytokines (such as IL-2 and Gamma Interferon) that message the cells that attack cancer cells or virus-infected host cells.
• The TH2 cells, on the other hand, secrete cytokines (such as IL-6 and TNF-alpha) which promote the production of antibodies.
• If the TH1 cells are underactive, diseases such as cancer and chronic viral diseases may develop.
• If the TH2 cells are too active, then autoimmune conditions, chronic inflammation or allergic symptoms may develop.
• For optimal immune function, both TH1 and TH2 cells need to function at the correct level.