Immune system

Human Immune System

The human immune system is made up of different components that allow labelling and elimination of foreign substances, as well as the regulation of these processes.

The functioning or malfunctioning of this system is therefore of vital importance to health and disease. Not only does it constitute the body's defensive system against foreign antigens, but a mulfunctioning of its regulatory processes can result in conditions such as autoimmune disease. A major area of interest is also the role of the different components in treatments to conditions such as leukaemia, where Graft vs Host Disease due to an inflammatory response launched against the donor's haematopoeitic transplant is a hurdle still to overcome.

Components of the Immune System

Physical Barriers

The first line of defence are physical barriers that prevent the pathogen or foreign substance from entering the body or, once entered, from harming it.

The skin is one of the most obvious exmaples. Not only does it provide physical protection from invasion, but the presence of antimicrobial substances and a low pH prevents pathogenic bacterial colonisation for example. As well as on the skin, the gut contains colonies of natural flora, non-pathogenic bacteria that provide a competitive environment for pathogenic strains.

Finally, lysozyme in tears helps defend the eye, a very sensitive organ which constitutes a gateway to the paranasal sinuses, from bacterial invasion.