Within the last 10 years, the immune system of ruminants, especially T cells and their interactions with other cells, has been an important topic of study for veterinary immunologists and an area of interest for medical and fundamental immunologists. This book brings together all the latest data on ruminant cell-mediated immunology. In the first half of the book, leukocytes and their membrane molecules and cytokines are reviewed. Markers, tissue distribution, functional characterization, ontogeny, cytokines, and histocompatibility are covered in depth in separate chapters. In the second half of the book, cell-mediated immune responses against infectious diseases such as East Coast fever, infectious bovine rhinotracheitis, foot and mouth disease, maedi-visna, and gastrointestinal nematodes are analyzed. The application of cytokines to ruminants against infectious diseases is also reviewed.