Why is AIDS considered a disease of the immunity system?

Acquired Immunodeficiency Syndrome (AIDS) is considered a disease of the immunity system because it severely weakens or impairs the body's ability to fight off infections and certain types of cancer. Here's why:

1. HIV Attacks Immune Cells: AIDS is caused by the human immunodeficiency virus (HIV), which primarily infects and destroys a type of white blood cell called CD4+ T cells, also known as helper T cells. These cells are crucial components of the immune system and play a central role in coordinating immune responses.

2. Depletion of CD4+ T Cells: As HIV replicates and spreads, it leads to a significant depletion of CD4+ T cells. This severely weakens the body's immune defenses, making it increasingly difficult to fight off infections and diseases.

3. Opportunistic Infections: Due to the compromised immune system, individuals with AIDS become susceptible to a wide range of opportunistic infections. These infections are caused by microorganisms that usually do not pose a significant threat to people with healthy immune systems. Examples of opportunistic infections associated with AIDS include Pneumocystis jirovecii pneumonia (PCP), candidiasis, cryptococcal meningitis, and Kaposi's sarcoma.

4. Increased Risk of Certain Cancers: In addition to opportunistic infections, individuals with AIDS are also at increased risk of developing certain types of cancer, such as Kaposi's sarcoma, non-Hodgkin's lymphoma, and cervical cancer. These cancers are often associated with the immunosuppression caused by HIV.

5. Chronic Inflammation: HIV infection leads to chronic inflammation in the body, further impairing immune function and contributing to the development of AIDS-related complications.

Overall, AIDS is considered a disease of the immunity system because HIV primarily targets and damages immune cells, specifically CD4+ T cells, leading to a weakened immune response, recurrent infections, and an increased risk of certain cancers.