The Immune System, Third Edition

By Donna Bozzone and Gregory Stewart

Praise for the previous edition:

SSLI "Honor Book," Science, Grades 7–12 category—Society of School Librarians International

The immune system is crucial to the normal functioning of the human body. As the body's "military," it prevents invaders from entering and destroys those who slip past its defenses. The Immune System, Third Edition discusses the human body's fundamental defense system, from its component parts to what happens when the body's defenses are breached. Common and uncommon immune disorders are also discussed, as are potential new therapies to enhance or repair the immune system. Packed with full-color photographs and illustrations, this absorbing book provides students with sufficient background information through references, websites, and a bibliography.

• Language: English
• Publisher: Chelsea House
• Release date: Aug 1, 2021
• ISBN: 9781646937219

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The Immune System, Third Edition

Copyright © 2021 by Infobase

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Contents

Chapters

How Important Is the Immune System?

Innate Immunity and Defenses

Cells, Tissues, and Organs of the Immune System

Humoral Immunity

Antibody Synthesis

Cell-Mediated Immunity

Importance of Vaccines

Allergies and Autoimmune Diseases

Immune Reactions as a Scientific Tool

Support Materials

Glossary

Bibliography

Further Resources

About the Authors

Index

Chapters

How Important Is the Immune System?

Introduction

You are probably familiar with many systems of the human body. The skeletal system includes the bones, which serve to support and protect the rest of the body. The muscular system allows the body to move, and the digestive system allows us to take in food and extract its energy to build and maintain the body. The respiratory system is responsible for bringing oxygen into the body and the circulatory system sends blood to every tissue and cell where that oxygen is delivered. It is relatively easy to understand the functions and the importance of these systems, but what about the immune system?

The immune system is extremely important to us. Its job is to help the body avoid and fight infections. The immune system also prevents the development of certain types of cancer. To illustrate the importance of this system, we will consider examples where the immune system does not function properly: infectious diseases, allergic reactions and autoimmune diseases. 

Infectious Disease and History

Every historical age of human history seems to be defined by one or more catastrophic disease. In medieval Europe, it was the black plague, or bubonic plague. From 1347–1353, outbreaks occurred in villages and cities throughout the continent and, in one estimate, led to the death of as much as one-half of Europe's population.¹ The histories of sub-Saharan Africa, India, and the Mediterranean region of Europe are marked with cycles of malaria, a disease transmitted by mosquitoes, that nearly one-half of the world's population is still at risk of contracting.² Tuberculosis became the principal disease of the Romantic and Victorian periods throughout Europe. This wasting disease was so prevalent that it became a central and recurring theme in much of the art and literature of the time. When you hear of a character suffering from or dying of consumption, the author is referring to tuberculosis. 

During periods of exploration and colonization, Europeans traveling to faraway places brought home with them exotic products, such as new fruits, silks, and spices, but they also returned with previously unknown diseases, including the sexually transmitted disease, syphilis. Eventually infectious disease outbreaks altered the history of the Western Hemisphere. Before their exposure to Europeans, Native Americans had been free from many of the infectious diseases that were common in Europe and the rest of the Old World. However, once they were exposed to these infectious diseases, the Native Americans were extremely likely to become sick from and succumb to these diseases. In one instance in 1520, a small band of conquistadors led by Hernán Cortés (allied with more numerous Native American rivals of the Aztecs) conquered Tenochtitlán, the capital of the Aztec empire, after smallpox killed half of the city's population, including the Aztec ruler Cuitláhuac.³ This pattern repeated itself again and again, throughout the Western Hemisphere as Europeans came into contact with Native American civilizations. Their germs caused catastrophic death in the Native American population.

Infectious disease shaped modern history too. At the turn of the 20th century, it was common for parents to have large families of six or more children as many children never lived to adulthood. Children often died from one of the rampant, childhood infectious diseases: influenza, measles, typhus, typhoid fever, and scarlet fever. During the 1920s and through the 1940s, the United States was devastated by polio, a disease that killed many children, and left many other children partially paralyzed.

Acquired Immune Deficiency Syndrome: AIDS

One of the most serious infectious diseases of the late 20th century, acquired immune deficiency syndrome (AIDS) continues to be a worldwide problem in the 21st century. AIDS is a global pandemic, affecting people on all continents except Antarctica. While AIDS is a significant health care challenge in the United States, there are areas of the world where AIDS is a much more serious problem. In 2019 it was estimated that eastern and southern Africa had 20.7 million people with HIV, or the human immunodeficiency virus, the causative agent for AIDS.⁴ Globally, 38 million people are afflicted with this progressive disease.⁵ At first, the onset is slow with only mild symptoms that can easily be mistaken for the common cold or flu. As AIDS progresses, the symptoms worsen. The patient becomes chronically ill and loses weight. In Africa, where HIV is thought to have originated, people call AIDS the wasting disease because of the relentless deterioration of health, coupled with the rapid loss of weight.

This graphic shows the global prevalence of HIV in adults (persons aged 15-49) in 2019.

Source: Infobase.

Although AIDS first became noticeable in the United States in gay men and in intravenous drug users, everyone is vulnerable to contracting the disease. AIDS does not specialize or discriminate.  Because HIV is spread by bodily fluids, activities where fluids are shared between people can be risky. These behaviors include sex, intravenous drug use, and blood transfusions. AIDS spreads by what people do, not according to who they are.

The History of AIDS in the United States

The manner in which the United States reacted to the first cases of AIDS is an interesting case study that reveals how bias can impact public health decisions and actions. 

In the 1960s and 1970s, decades that preceded the AIDS pandemic, the United States vigorous efforts to fight infectious disease was considered very successful. For example, smallpox, once one of the most feared diseases in the world, had been completely eliminated. The United States was also well on its way to eradicating another devastating disease, tuberculosis. So many diseases were being managed successfully with vaccines and antibiotics that some of the leading scientists of the time suggested that medical microbiology would soon become an extinct area of study. Colleges and universities that trained microbiologists began to reduce the focus on disease and increase the emphases on biochemistry, molecular genetics, and environmental microbiology. Unfortunately, this overconfidence had consequences. When new cases of unexplained