Immunodeficiency

Immunodeficiency, also known as immunocompromise, is a state in which the <a href="/facts/Immune_system/HRCTf1pb">immune system</a>'s ability to fight <a href="/facts/Infectious_disease/182XrncP">infectious diseases</a> and <a href="/facts/Cancer/PVW6n1D0">cancer</a> is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that affect the patient's immune system. Examples of these extrinsic factors include <a href="/facts/HIV/ulY2rgzu">HIV</a> infection and <a href="/facts/Environmental_factor/T6FvWue8">environmental factors</a>, such as <a href="/facts/Nutrition/SMJ3Dhfs">nutrition</a>. Immunocompromisation may also be due to <a href="/facts/Genetic_diseases/hFqt2NLn">genetic diseases</a>/flaws such as <a href="/facts/Severe_combined_immunodeficiency/gNfMUSp9">SCID</a>.
In clinical settings, <a href="/facts/Immunosuppression/22GHUHkr">immunosuppression</a> by some drugs, such as steroids, can either be an <a href="/facts/Adverse_effect/vAhfbr1J">adverse effect</a> or the intended purpose of the treatment. Examples of such use is in <a href="/facts/Organ_transplant/1jNvVJn6">organ transplant</a> surgery as an anti-<a href="/facts/Transplant_rejection/d9jSqs2x">rejection</a> measure and in patients with an overactive immune system, as in <a href="/facts/Autoimmune_disease/sojBeQ7t">autoimmune diseases</a>. Some people are born with intrinsic defects in their <a href="/facts/Immune_system/HRCTf1pb">immune system</a>, or <a href="/facts/Primary_immunodeficiency/7l8U9MKM">primary immunodeficiency</a>.
A person who has an immunodeficiency of any kind is said to be immunocompromised. An immunocompromised individual may particularly be vulnerable to <a href="/facts/Opportunistic_infection/d6ndMynw">opportunistic infections</a>, in addition to normal <a href="/facts/Infection/182XrncP">infections</a> that could affect anyone. It also decreases <a href="/facts/Cancer_immunosurveillance/wu5YzX6d">cancer immunosurveillance</a>, in which the immune system scans the body's cells and kills <a href="/facts/Neoplastic/K0ytzmPz">neoplastic</a> ones. They are also more susceptible to infectious diseases owing to the reduced protection afforded by <a href="/facts/Vaccines/QcXzLug2">vaccines</a>.

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Immunodeficiency