The innate immune response is a crucial component of early resistance to infection, and it is now revealing increasing levels of complexity. The ability to modify the genome in vivo, has facilitated understanding of complex interactions between leucocytes and other components of the immune system, and phenotype-driven strategies using chemical mutagenesis have placed another powerful weapon in the armamentarium. In, provides detailed prools and practical advice on a variety of modern approaches to the study of leucocytes and their products. Written in the highly successful series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory prools, and key tips on troubleshooting and avoiding known pitfalls.