Chapter 17 - Molecular Basis of Diseases of Immunity

Abstract

The human immune system has evolved over millions of years to protect against infection by microorganisms. It is remarkable in both its complexity and its effectiveness. Without a functioning immune system, humans cannot survive past the first few months of life. Despite this highly evolved system, infectious diseases were by far the most common cause of death until the 20th century. The increase in life expectancy seen in the past 100years or so reflects progress in control of infectious diseases, including improved hygiene, vaccines, and antimicrobial drugs. However, the improved control of infections in modern society may have come at the expense of increasing the risk for autoimmune and allergic diseases. Following a brief review of some of the more important cells and molecules of the immune system. This chapter covers the pathophysiology of several major syndromes of immune dysfunction including diseases of deficient immunity (primary and acquired immunodeficiencies), hyperactive immunity (hypersensitivity), and dysregulated immunity (autoimmune diseases).