This book focuses on new research advances in the field of immunology which is the study of the body's protection from foreign macromolecules or invading organisms and the responses to them. These invaders include viruses, bacteria, protozoa or even larger parasites. In addition, immune responses are developed against our own proteins (and other molecules) in autoimmunity and against our own aberrant cells in tumour immunity. The first lines of Defence against foreign organisms are barrier tissues such as the skin that stop the entry of organism into our bodies. A second line of defence is the specific or adaptive immune system which may take days to respond to a primary invasion (that is infection by an organism that has not hitherto been seen).