Ageing and the immune system

Recognising invading foreign organisms, preventing their spread and ultimately clearing them from the body throughout life is the central role of the immune system. In a healthy adult, the immune system is composed of approximately 1012 cells which interact with each other to produce both effector molecules and cells which defend the tissues of the body against potential pathogens. Unfortunately, like all biological systems, there is normal wear and tear, and with advancing age, the immune system shows a gradual loss of function. However, because each individual differs in their genetic makeup and has been exposed to a different range of environmental factors, this functional decline is not uniform and predictable. There is no certain age at which this process begins and no defined pathway or identifiable sequence of loss of function. The result is considerable variation within the aged population in the ability of an individual to respond productively to potential pathogens and vaccines. Current work is directed at mapping the changes in the immune system with age with a view to identifying any common triggers of deterioration in function. This in turn might lead to an opportunity to reverse the degradation process and thus to extend the period of fully effective protection.