<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
Skip Navigation
Our Terms of Use (click here to view) have changed. By continuing to use this site, you are agreeing to our new Terms of Use.


When the immune system stops working minor infections can become life-threatening.

Atoms Practice
Estimated2 minsto complete
Practice Immunodeficiency
This indicates how strong in your memory this concept is
Estimated2 minsto complete
Practice Now
Turn In

Which is stronger?

You or little tiny pathogens? Usually you are. Normally your body can put up a strong defense against enemy pathogens. But what if it can't? What happens if your immune system is "sick"?


Immunodeficiency occurs when the immune system is not working properly. As a result, it cannot fight off pathogens that a normal immune system would be able to resist. Most commonly, immunodeficiency diseases occur when T or B cells (or both) do not work as well as they should, or when your body doesn't produce enough antibodies.

Rarely, the problem is caused by a defective gene. Inherited immunodeficiency disorders that affect B cells include hypogammaglobulinemia, which usually leads to respiratory and gastrointestinal infections, and agammaglobulinemia, which results in severe infections early in life, and is often deadly.

More often, immunodeficiency is acquired during a person’s lifetime. Immunodeficiency may occur for a variety of reasons:

  • The immune system naturally becomes less effective as people get older. This is why older people are generally more susceptible to disease.
  • The immune system may be damaged by other disorders, such as obesity or drug abuse.
  • Certain medications can suppress the immune system. This is an intended effect of drugs given to people with transplanted organs. In many cases, however, it is an unwanted side effect of drugs used to treat other diseases.
  • Some pathogens attack and destroy cells of the immune system. An example is the virus known as HIV. It is the most common cause of immunodeficiency in the world today.




  • In an immunodeficiency disease, the immune system does not work normally. As a consequence, it cannot defend the body.


  1. What is immunodeficiency?
  2. List three possible reasons for acquired immunodeficiency.

Notes/Highlights Having trouble? Report an issue.

Color Highlighted Text Notes
Please to create your own Highlights / Notes
Show More


HIV (human immunodeficiency virus)

Virus transmitted through body fluids that infects and destroys helper T cells and eventually causes acquired immunodeficiency syndrome (AIDS).


Inability of the immune system to fight off pathogens that a normal immune system would be able to resist.

Image Attributions

Explore More

Sign in to explore more, including practice questions and solutions for Immunodeficiency.
Please wait...
Please wait...