The bodys defence mechanisms

The various systems of the body have a range of mechanisms for dealing with foreign materials, germs and viruses that enter the body. 

Foreign bodies on the surface of the eye may cause weeping (lachryma-tion) which can flush out some of the particles but not those that have become embedded in the eye. Tears will also dilute irritating chemicals. 

A second t) e of white cell, the pol5unorphonuclear leukocyte (PMNL) is more common than the macrophage and makes up 60% of all white blood cells. These cells are attracted to sites of infection by the chemicals that are released by invading bacteria. Special cells, known as B l3unpho-cytes, produce antibodies that are chemicals that can attach themselves to the surface of various germs thus rendering them ineffective, but any particular antibody can only bind to one bacterium. T cytoxic (killer) cells can kill cells directly. They attacked cells filled with viruses before the virus can reproduce and are involved in the defence of the body against cancer cells. 

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Many other applications for plasma polymers in the Life Sciences have been dted, often in relation to implantable medical devices or materials, with the goal of concealing the device from the bodies defence mechanisms, or improving cell colonisation of the material, e.g. endothelial cell growth into vascular grafts. A number of excellent studies from the group of Hans Griesser (CSIRO, Australia) describe the use of plasma polymers as substrates to which biomolecules can be immobilised. These immobilisations have been demonstrated to enhance the medium-term acceptability of contact lens materials and may prove relevant to implantable devices. 

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