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1st August 2023
Causes of Immunocompromisation
Immunocompromisation, or immunodeficiency, refers to a state in which the ability of a person’s immune system to combat disease is either diminished or absent. It is most often secondary (Table 4). Primary immunodeficiency is rare and due to congenital developmental defects or genetic abnormalities present from birth (Table 5).
Immunocompromised patients are more likely to be severely affected by common pathogens and more vulnerable to certain pathogens that rarely cause illness in patients with fully-functioning immune systems, i.e. opportunistic infections. Many of these are associated with HIV, as explained in the previous section.
Selected causes of acquired immunodeficiency
| Infectious diseases | Predominantly HIV |
| Autoimmune diseases | Systemic lupus erythematosus Rheumatoid arthritis Type 1 diabetes Addison’s disease |
| Haematological diseases | Malignancies leading to myelosuppression |
| Trauma or surgery | Damage to the spleen, subsequent splenectomy |
| Immunosuppressive drugs | Corticosteroids Anti-TNF drugs Cytotoxic chemotherapy |
Table 4: Selected causes of acquired immunodeficiency
Selected causes of primary immunodeficiency
| Condition | Features |
|---|---|
| DiGeorge syndrome | Caused by T lymphocyte deficiency due to congenital developmental failure of parathyroid glands, aortic arch and thymus (where T lymphocytes are developed). Presents with characteristic facies, hypoparathyroidism, cardiac defects and susceptibility to infections in the early months of life. |
| Hyper IgM syndrome | An X-linked defect in the CD40 ligand gene affects both B and T lymphocytes, meaning only immature IgM antibodies can be produced by B lymphocytes. Leads to susceptibility to opportunistic infections. |
| Selective IgA deficiency | The most common primary immunodeficiency syndrome is found in 1 in 600 northern Europeans. The exact aetiology is unknown and has variable clinical features – it can present at any age, typically with recurrent pyogenic infection. |
Table 5: Selected causes of primary immunodeficiency
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