Although babies born with defective immune systems are rare, the world is experiencing the horror of defective immunity in thousands of people who have AIDS (acquired immune deficiency syndrome). They acquired this condition from infection with a virus that knocks out a key white blood cell in the body’s delicate immune system. Without effective immunity, AIDS patients fall prey to bacteria and fungi that live harmlessly on the skin or inside healthy persons. Resultant infections ravage the body. AIDS can kill almost all who contract it, making it the most deadly illness of modern times. In 1996, scientists discovered medicines that slow down the growth of the AIDS virus in an infected person. At the same time, other drugs plus antibiotics control the lethal infections that commonly afflict people with AIDS. This new era in AIDS control has reduced the growth of the AIDS virus to extremely low levels so as to be immeasurable. People with AIDS, who at first expected to live 2 or 3 years, can now look forward to staying alive for at least 10 years.
The new knowledge about immunity has allowed scientists to move fast against AIDS. The first cases in the United States were reported in 1981 as a strange pneumonia. But, in a year or two, scientists had pinpointed the defect in immunity. In 1984, they isolated the killer virus. Although researchers hailed the identification of HIV as signaling the development of a vaccine, over 10 years have elapsed without a usable one. That’s because the AIDS virus is constantly changing (somewhat like the influenza virus, but much more rapidly).
Herpes viruses live forever in nerve cells. Some scientists believe they are triggered by cold, heat, fever, chemicals, or menstruation. The virus grows out of the affected nerve cells and attacks other tissues. Shingles is really the reactivation of an old chicken pox virus, responding, some theorize, to the same triggers.
Four major discoveries have brightened the promise of immunology:
• The unraveling of the complex way in which the different types of white blood cells cooperate to attack foreign substances that get into the body
• The discovery of chemicals released by the cells that give signals for white cell action. Interferon and interleukin, for instance, are both promising cancer treatments.
• The development of genetic engineering. Scientists now know how to alter the biology of common sewage bacteria so that the germs can create unlimited amounts of human chemicals like insulin, interferon, and interleukin.
• The creation of a strange and wonderful cell called a hybridoma. These hybrid cells can produce boundless amounts of antibodies – chemicals that attack invading viruses, bacteria, or fungi. Hybridoma antibodies also hold promise against cancer.