So why do I get some illnesses lots of times?
We seem to get some infections, like colds, year in and year out. If our immune system remembers the invading germ and quickly gets rid of it why do we keep getting colds? This is because the antigens that our immune system recognises and the antibodies that our body produces are very specific. Think of a padlock and key. Although many padlocks look the same, and many keys look the same, only one specific key will fit one specific padlock. If the padlock changes at all, even slightly, the key will not fit. Now imagine that the antigen (on the germ) is the padlock and the antibody (from the immune system) is the key. Some germs are good at changing their antigens (or padlock) so that when they infect us a second time our immune system does not recognise the padlock (or antigen) that the germ is carrying. That is why when we have one cold we are not protected against getting another, because the virus that causes a cold will probably have changed its antigen by the next time we are infected. This is also why the HIV virus is so difficult to treat. The antigens on HIV change so rapidly that the immune system is not able to act quickly enough to get rid of it from the body. (See the HIV section for more details).
Date of Posting: 10/01/2003
Date of next Review: 15/01/2005
How does my body protect itself against infection?
What happens if the microbes get through the first defences (the innate response)?
What is the adaptive immune response?
Why do I only get some illnesses once?
Why may I need to take antimicrobials?
Immune System; Immunity; Immunity, Natural; Immunity, Active; Immunity, Cellular; Antigens; Antibiodies