The role of the innate immune system has been underestimated over the years, but findings during the last decade have revealed how important it is in initiating and shaping the adaptive immune response.

The innate immune system comprises the cells and their mechanisms that defend the host from infection by antigens in a nonspecific manner. Therefore, this is a necessary supplement to the antigen specific or adaptive immune system. Both systems consist of humoral and cellular components, the innate system additionally also includes anatomical barriers.

This book will update our knowledge about the various cellular components (e.g. NK-cells, microglial cells, macrophages) and associated factors (e.g. antimicrobial peptides, mucins, toll-like receptors). Also, the cooperation of innate and adaptive immune system will be discussed. After presentation of the physiological role of the innate immune system, its role in autoimmune disorders, tumorigenesis and infection (e.g. TB) will be analyzed.