Acquired immune deficiencies are conditions that develop after birth, in which the body’s immune system becomes weakened or compromised, making it less able to fight off infections and certain diseases. Unlike primary (congenital) immunodeficiencies, which are inherited, acquired deficiencies are typically caused by external factors or underlying medical conditions.
Causes:
Acquired immune deficiencies can result from various factors that impair the normal functioning of the immune system:
- Infections:
- Human Immunodeficiency Virus (HIV): The most well-known cause. HIV attacks and destroys CD4+ T cells, which are crucial for immune function, leading to Acquired Immunodeficiency Syndrome (AIDS) in its advanced stages.
- Other viral infections: Some viruses (e.g., Epstein-Barr virus, cytomegalovirus, measles) can temporarily suppress the immune system.
- Severe bacterial or fungal infections: Can overwhelm and exhaust the immune system.
- Malnutrition: Severe deficiencies in protein, vitamins (e.g., A, C, D, B vitamins), and minerals (e.g., zinc, selenium) can significantly impair immune function.
- Cancers:
- Cancers of the immune system: Leukemias, lymphomas, and multiple myeloma directly affect the production and function of immune cells.
- Other cancers: Advanced cancers can weaken the immune system.
- Medical Treatments:
- Chemotherapy and Radiation Therapy: Used in cancer treatment, these therapies kill rapidly dividing cells, including immune cells in the bone marrow.
- Immunosuppressive medications: Used to prevent organ transplant rejection or treat autoimmune diseases (e.g., corticosteroids, biologics like TNF inhibitors) intentionally suppress the immune system.
- Chronic Diseases:
- Kidney failure (uremia): Impairs immune cell function.
- Diabetes: Can lead to impaired neutrophil function and increased infection risk.
- Liver disease (cirrhosis): Affects the production of immune proteins and can lead to immune dysfunction.
- Autoimmune Disorders: While some autoimmune diseases involve an overactive immune response, the chronic inflammation and treatments used can sometimes lead to a secondary immunodeficiency.
- Splenectomy (removal of the spleen): The spleen plays a vital role in filtering blood and producing immune cells, so its removal increases susceptibility to certain bacterial infections.
- Aging: The immune system naturally becomes less effective with age (immunosenescence), making older adults more susceptible to infections and less responsive to vaccines.
Symptoms:
The symptoms of acquired immune deficiencies are primarily related to recurrent, severe, or unusual infections that a healthy immune system would normally fight off. Symptoms can vary based on the underlying cause and the specific immune cells affected:
- Frequent and recurrent infections: Such as pneumonia, bronchitis, sinusitis, ear infections, skin infections.
- Severe infections: Infections that are unusually severe or prolonged.
- Infections with unusual or opportunistic organisms: Germs that typically don’t cause illness in healthy individuals.
- Poor response to standard antibiotic treatment.
- Slow wound healing.
- Persistent fatigue.
- Unexplained weight loss.
- Swollen lymph nodes.
- Other symptoms related to the underlying cause: (e.g., fever, night sweats, diarrhea, skin rashes in HIV/AIDS; symptoms of cancer or chronic organ disease).
Diagnosis:
Diagnosing acquired immune deficiencies involves a thorough medical history, physical examination, and various laboratory tests to assess immune function and identify the underlying cause:
- Medical history and physical exam: The doctor will ask about recurrent infections, family history, lifestyle, and any underlying medical conditions or medications.
- Blood tests:
- Complete Blood Count (CBC) with differential: To count white blood cells (including lymphocytes, neutrophils), red blood cells, and platelets.
- Immunoglobulin levels (IgG, IgA, IgM): To measure the levels of different types of antibodies.
- Lymphocyte subsets: To count specific types of immune cells, such as CD4+ T cells (especially for HIV).
- Antibody response to vaccines: To assess how well the immune system produces antibodies after vaccination.
- Tests for specific infections: (e.g., HIV test, hepatitis tests).
- Tests for underlying conditions: (e.g., blood glucose for diabetes, kidney/liver function tests, cancer markers).
- Bone marrow biopsy: May be performed if a primary bone marrow disorder or cancer is suspected.
- Imaging studies: (e.g., chest X-ray, CT scan) to look for infections or other abnormalities.
Treatment:
Treatment for acquired immune deficiencies focuses on managing the underlying cause, preventing infections, and supporting immune function.
- Treating the underlying cause:
- Antiretroviral therapy (ART) for HIV: Suppresses the virus, allowing the immune system to recover.
- Treating malnutrition: Nutritional supplements and dietary changes.
- Cancer treatment: Chemotherapy, radiation, surgery.
- Managing chronic diseases: (e.g., diabetes control, kidney dialysis).
- Adjusting medications: Reducing or changing immunosuppressive drugs if possible.
- Preventing and treating infections:
- Antibiotics, antifungals, antivirals: To treat active infections.
- Prophylactic medications: May be prescribed to prevent infections in severely immunocompromised individuals.
- Vaccinations: Recommended for many individuals, though response may be reduced. Live vaccines may be contraindicated.
- Good hygiene: Frequent handwashing, food safety.
- Immune support therapies:
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- Intravenous Immunoglobulin (IVIg) or Subcutaneous Immunoglobulin (SCIg): For individuals with severe antibody deficiencies, providing ready-made antibodies to fight infections.
- Granulocyte colony-stimulating factors (G-CSF): To stimulate neutrophil production in some cases of neutropenia.
- Stem cell transplantation: For severe cases of bone marrow failure or certain cancers.
Managing acquired immune deficiencies requires a comprehensive and ongoing approach, often involving a team of specialists, to minimize the risk of infection and improve overall health.