The body's operating systems are interconnected and highly complex, especially the immune system. In immunology, it's very easy to create one evil by trying to correct another, so a thorough knowledge of the immune system is essential for anyone wishing to enter this field. That's why, through this book, we want to help scientists to carry out their research wisely. We've gone one step further by synthesizing the molecular mechanisms that can explain the immune system and thus cause serious problems for the organism if it malfunctions. We've tried to write up not only some experimental protocols as examples to give some ideas of scientific approach to immunomodulation, but also a list of some immunomodulatory products. This book will help all researchers in any field of life, because immunology is at the "heart" of all branches of animal physiology. It is therefore a leading branch of life science. It's clear that the symptoms of any disease appear when the natural defense systemis weakened. The imperative to know the basics of this system must therefore concern all researchers, and so this book is timely and appears to be the solution.