This book represents Part 1 of a two-part monograph in which the emerging role of "Innate Alloimmunity" in organ transplantation is comprehensively presented and described for the first time worldwide. In fact, the last decade has witnessed the exciting emergence of innate immunity - a new area in immunology, transplantology, vascular biology and other medical disciplines - that has revolutionized our understanding not only of host-parasite interactions and their impact on defense mechanisms in infectious diseases but also of transplant recipient-donor organ interactions and their impact on acute and chronic allograft rejection. This Part 1 of the monograph, devoted to the topic of innate immunity and host defense, conveys to the reader the basic knowledge from this expanding field of medical research in an instructive and convincing way. Accordingly, the book highlights some of the most important aspects of host defense that may be of particular relevance for those clinicians and researchers working in the field of organ transplantation and its related medical disciplines.In carefully selected seven chapters, the author addresses seven major topics dedicated to (1) the evolution of oxygen toxicity and its role in host defense, (2) some historical remarks to innate immunity, (3) selected evolutionary aspects of innate immunity, emphasizing that defense responses in primitive life forms like plants and insects share a clear evolutionary relationship with human responses to infection, (4) the whole family of innate immune cells including macrophages, leukocytes, mast cells, epithelial cells and endothelial cells as well as innate humoral factors including complement and natural IgM, (5) pattern recognition receptors and their exogenous agonists (ligands) in host defense against pathogens including TLRs, NLRs, CLRs, and RLHs, (6) innate host defense peptides and soluble mediator substances, and (7) dendritic cells translating innate to adaptive immunity. Every chapter closes with a detailed review of the literature that comprises a wealth of valuable references. What makes this book special is a large number of accompanying colored figures that, for example, plausibly illustrate the different signaling pathways triggered by the various recognition receptors and leading to the execution of distinct functions of various cells of the innate immune system. The book must be considered an invaluable resource for anyone interested in this emerging field of transplant immunology - in particular, clinicians who work in the field of transplantation or transplantation-related medical disciplines, and strive for exploring innate immune mechanisms involved in host defense against various infections that plague their patients.