How Immunosuppression in AIDS is Related to Opportunistic Infections and Inflammation

What is Immunosuppression?

Immunosuppression is the suppression of the body’s innate ability to ward off disease and infection. This suppression may be the result of a disease that targets the immune system, such as the human immunodeficiency virus (HIV), or as a consequence of pharmaceutical agents used to fight certain conditions, like cancer.

How Does HIV Cause Immunosuppression?

HIV is a retrovirus that infects and destroys CD4+ T cells, which are a type of white blood cell that plays a key role in coordinating the immune response. As the number of CD4+ T cells declines, the immune system becomes less able to fight off infections and diseases, especially those that are rare or uncommon in healthy people. These are called opportunistic infections, because they take advantage of the weakened immune system.

Some examples of opportunistic infections that can affect people with HIV are:

  • Tuberculosis (TB), a bacterial infection that affects the lungs and other organs
  • Pneumocystis pneumonia (PCP), a fungal infection that causes severe respiratory problems
  • Cryptococcal meningitis, a fungal infection that causes inflammation of the brain and spinal cord
  • Toxoplasmosis, a parasitic infection that can damage the brain, eyes, and other organs
  • Cytomegalovirus (CMV), a viral infection that can cause blindness, diarrhea, and other complications
  • Kaposi’s sarcoma (KS), a type of cancer that causes purple or brown lesions on the skin and mucous membranes
  • Non-Hodgkin’s lymphoma (NHL), a type of cancer that affects the lymph nodes and other tissues

The presence of an opportunistic infection or a CD4+ T cell count below 200 cells per microliter of blood is used to diagnose acquired immunodeficiency syndrome (AIDS), which is the most advanced stage of HIV infection.

How Does Immunosuppression in AIDS Lead to Inflammation?

In some cases, when people with HIV start antiretroviral therapy (ART), which is a combination of drugs that suppress HIV replication and restore CD4+ T cell levels, they may experience a paradoxical worsening of their symptoms. This is called immune reconstitution inflammatory syndrome (IRIS), and it occurs when the recovering immune system mounts an excessive inflammatory response to a previously acquired opportunistic infection3.

IRIS can manifest as fever, rash, swollen lymph nodes, organ dysfunction, or worsening of the existing opportunistic infection. IRIS can be life-threatening if not treated promptly and appropriately. The risk of IRIS depends on several factors, such as:

  • The type and severity of the opportunistic infection
  • The degree and duration of immunosuppression before starting ART
  • The speed and magnitude of immune recovery after starting ART

IRIS usually occurs within the first few weeks or months of starting ART, but it can also occur later. The treatment of IRIS may involve anti-inflammatory drugs, such as corticosteroids, or antibiotics or antifungals to treat the underlying opportunistic infection.


Immunosuppression in AIDS is related to opportunistic infections and inflammation in several ways. HIV causes immunosuppression by destroying CD4+ T cells, which makes the body vulnerable to opportunistic infections that can cause serious complications and define AIDS. Immunosuppression in AIDS can also lead to inflammation when the immune system recovers after starting ART and reacts excessively to a latent opportunistic infection. This condition is called IRIS and requires prompt diagnosis and treatment. Therefore, it is important for people with HIV to monitor their CD4+ T cell count regularly and take ART as prescribed to prevent or manage immunosuppression in AIDS.

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