Immune system is responsible for defending the body against disease causing agents whether internal or external. It generates antibodies to counter possible infections. Immunology is a rapidly progressing discipline playing a vital role in diverse fields of medical science such as oncology, parasitology, organ transplantation, etc. This book aims to shed light on some of the unexplored aspects and recent researches in this field. Different approaches, evaluations, methodologies and advanced studies have been included in this book. Scientists and students actively engaged in this area will find this book full of crucial and unexplored concepts.