Immunodeficiency is caused by either primary (congenital or inherited) factors or secondary (acquired) factors.
Immunodeficiency occurs when the immune system is weakened, making the body less able to fight off infections and diseases. Causes are broadly categorized into two main types: primary and secondary.
Primary Immunodeficiency Diseases
Primary immunodeficiency diseases (PIDs) are genetic disorders that affect the development or function of the immune system. They are often inherited and can impact various parts of the immune system, including:
- B cells (antibody production)
- T cells (cellular immunity)
- Phagocytes (cells that engulf pathogens)
- The complement system (a group of proteins aiding immunity)
While the reference only explicitly names one primary immunodeficiency ("Selective immunoglobulin A deficiency is also a primary immunodeficiency"), it's important to know that PIDs encompass over 400 different conditions.
Examples of PIDs:
- Severe Combined Immunodeficiency (SCID)
- Common Variable Immunodeficiency (CVID)
- X-linked Agammaglobulinemia (XLA)
- Selective Immunoglobulin A Deficiency (mentioned in the reference)
These conditions are present from birth, although symptoms may appear later in life depending on the specific disorder.
Secondary Immunodeficiency
Secondary immunodeficiency is the most common type and is acquired later in life due to external factors or underlying medical conditions. Unlike PIDs, these are not genetic but result from other diseases, medical treatments, or environmental exposures.
According to the provided reference, secondary causes of immunodeficiency include steroids, nutrient deficiency, obesity, acquired immune deficiency syndrome (AIDS), or other viral infections.
Let's break down these specific acquired causes:
- Steroids: Long-term or high-dose corticosteroid use (like prednisone) can suppress the immune system.
- Nutrient Deficiency: Lack of essential vitamins and minerals necessary for immune function can weaken defenses.
- Obesity: Excessive body weight can lead to chronic inflammation and impair immune responses.
- Acquired Immune Deficiency Syndrome (AIDS): Caused by the human immunodeficiency virus (HIV), AIDS severely damages the immune system, particularly T cells.
- Other Viral Infections: Beyond HIV, other viruses like measles, influenza, and certain herpesviruses can temporarily or permanently weaken immune function.
Common Secondary Causes:
| Cause | Description | Impact on Immune System |
|---|---|---|
| AIDS (HIV infection) | Viral infection damaging T cells | Severe suppression, increased susceptibility to infections |
| Certain Medications | Steroids, chemotherapy, immunosuppressants | Suppress immune cell activity or production |
| Malnutrition | Lack of essential nutrients | Impairs immune cell development and function |
| Obesity | Chronic inflammation, metabolic changes | Can impair immune responses |
| Other Chronic Illnesses | Diabetes, kidney disease, certain cancers, viral infections | Can directly or indirectly weaken immune function |
| Splenectomy | Removal of the spleen | Reduces ability to filter blood and produce antibodies |
Understanding the cause of immunodeficiency is crucial for effective treatment and management, often involving preventing infections and treating the underlying condition.
