Preface

 About 100 years ago, there was the very real fear of allograft rejection reactions when deciding on organ transplantation and blood transfusion. On facing this fear, scientists began to unravel the way tissue rejection occurs and find possible implications for its inhibition. The observation of excellence in tissue transplantation between identical twins suggested a genetic component to donor-recipient compatibility. Consequently, incompatibility of ABO blood groups—which are inherited—emerged as the fundamental factor for rejection reactions. This initial realization was among the first clues to the crossword of immunogenetics. However, the determining factor that yielded the fruit of immunogenetics dates back to the late twentieth century when human leukocyte antigen (HLA) molecules and genes controlling their expression were introduced as the heart of the allograft rejection problem. In this manner, immunity and genetics are closely linked with the discovery of hereditary varieties of immune responses.

The introductory chapter of *Immunogenetics* provides an overview of the most important implications of immunogenetics after a brief introduction to the HLA system and its immunological function.

 Despite its initial rejection, the manuscript introducing Western blotting, also known as immunoblotting, was published in the early 1980s. Since then, the scientific community is still interested in adopting different Western blotting approaches to detect immunologic proteins in biological samples. The second chapter explores in detail the value of Western blotting as an immunoassay in today's world.

 In addition to rejection reactions, HLA molecules expressed by tumor cells can drive tumor development and play a critical role in avoiding detection by the immune system. In Chapter 3, the dynamic interaction between immune escape mechanisms and HLA regulation is presented.

Psychoneuroimmunology is a discipline with roots that connect the brain, behavior, and immunity. Findings of immunogenetic abnormalities that influence neurocircuitry and behavior have made this field especially interesting. Chapter 4 is dedicated to reviewing such research.

Tuberculosis is a potentially serious global health problem caused by *Mycobacterium tuberculosis* (Mtb) in humans. Different immune cells, for example, macrophages, dendritic cells, neutrophils, and natural killer cells, are induced in response to Mtb infection. Genetic alteration of antituberculosis immune responses has been associated with predisposition to different forms of tuberculosis. The last chapter discusses the immunogenetics of tuberculosis along with potential implications for immunotherapy.

We are very pleased to have had the opportunity to write this book on immunogenetics for IntechOpen, which is continuously attempting to open scientific minds

by publishing open access books. We hope that this book has, though concisely, answered some immunogenetic questions.

> **Nima Rezaei**  Tehran University of Medical Sciences, Tehran, Iran

## **Chapter 1**
