The immunology as a subject has grown immensely in the last one hundred years. But the theoretical explosion of knowledge has not been adequately utilized to manipulate the immune system to our advantage except in the domain of vaccines and designing certain immunodiagnostic tests based on antigen specificity. This book contains chapters on the history of immunology, host parasite relationship, basic immunology (antigen and antigen recognizing molecules), diagnostic Immunology, complements, immune response, hypersensitivity, autoimmunity, immunodeficiency states, immunological tolerance, immunohematology, transplantation immunology, tumor immunology, vaccines and immunity against bacteria, parasites, viruses and fungi. The goals for this second edition of Textbook of Immunology by Mohanty and Leela is to provide a brief, accurate and update presentation of those aspects of Immunology that are of particular significance in the field of clinical infection, diagnostic immunology and other fields of biological sciences. The chapters have been updated with essentials which include antigen receptors in innate and adaptive immunity, monoclonal antibodies in diagnosis research and therapy, future prospects B cell and T cell repertoire and their subpopulation, autoimmune diseases, immunodeficiency states, cancer vaccines, immunotherapy, etc. In view of their importance in immunotherapy, cytokines have been elaborately and explicitly discussed in relation to their receptors, the varied properties such as pleiotropy, redundancy, synergism, etc. and the unpredictability in the management and treatment of inflammation, infection, allergy, autoimmune diseases and neoplastic conditions. It is desired that the second edition of Textbook of immunology will invite today’s students, researchers, practitioners not only to acquire familiarity with the immune system but also to delve into the depth to explore and exploit the benefits that will make them doctors, researchers, practitioners and teachers.