This book has stood the test of time as a core text, giving a concise introduction to immunology. The book focuses on basic science but informs the reader of the clinical relevance where appropriate for a clear understanding of the cells, molecules and processes of the immune system. The book has been thoroughly updated to include new sections on: the interaction between innate and adaptive immunity; the roles and regulation of T-cell subpopulations, cytokines and adhesion molecules; genetic and environmental factors affecting susceptibility to infection, immunodeficiency and atopic disease.