The book comprises of five chapters and describes the origin, production and scope of cytokines, which are the most important molecules of immune system around which the field of functional immunology revolves. This book describes how the immune system responds to injuries and insults by foreign antigens (bacteria, viruses etc.) and produces cytokines, which then, through various immune response mechanisms, protect the body against pathogenic invasions, how these glycoproteins are involved in the differentiation and maturation of immune cells, how lymph nodes are involved in concentrating the different forms of cytokines, how immunogenicity of a cytokine is affected and how a cytokine is related to the immune response. Various types of cytokines and the organization and expression of cytokine receptors are described separately. The properties, mechanistic function and therapeutic cytokines are also discussed in separate chapters. The characteristics, production and important roles played by different cytokines in research, diagnostics and therapeutics is described separately. Lastly the role of cytokines and chemokine's in infectious diseases and their importance in the detection of various kinds of diseases like cancer, HIV-AIDS, tuberculosis, malaria etc. are discussed in detail separately. The book contains a reasonable number of diagrams, flowcharts and tables. Besides this, various interesting and self-explanatory illustrations are incorporated to make the book useful to the students for whom it is written. The question bank, which includes long answer type, short answer type and multiple choice questions with their answers at the very end of each chapter, is developed to get a full grasp of the topic.