Knowra Immunodeficiency Immunodeficiency Immunodeficiency is inadequate immune-system function caused by missing or impaired components. It increases susceptibility to infections and can raise the risk of certain cancers and other diseases.
Innate immunity : The rapid, broadly acting defenses present from birth, including barriers, phagocytes, and complement. Defects in these first-line defenses can cause severe bacterial and fungal infections.
Primary immunodeficiency : An immunodeficiency caused by inherited or developmental defects in immune-system components. Its mechanism begins with a genetic or developmental defect rather than an external suppressive cause.
Complete blood count : A blood test that measures blood-cell numbers, including white blood cells and their major types. Low lymphocyte or neutrophil counts can provide an early clue to immunodeficiency.
Severe combined immunodeficiency : A group of inherited disorders causing profound impairment of T-cell function and often B-cell or natural-killer-cell function. It exemplifies a profound combined defect that threatens survival without early intervention.
Autoimmunity : Autoimmunity is immune recognition and attack directed against the body's own tissues. Autoimmunity involves harmful immune activity, unlike the inadequate defenses defining immunodeficiency.
Adaptive immunity : Antigen-specific immune defense mediated by B cells, antibodies, and T cells, with capacity for immune memory. Failures in this arm impair targeted responses and can leave characteristic gaps in immune protection.
Secondary immunodeficiency : An immunodeficiency acquired through illness, malnutrition, medication, or another external or systemic cause. Here the immune deficit follows a disease or exposure, rather than an inborn immune defect.
Lymphocyte proliferation assay : A laboratory test measuring how lymphocytes multiply after stimulation by antigens or mitogens. It tests whether lymphocytes function, not merely whether they are present.
X-linked agammaglobulinemia : An inherited disorder, usually caused by BTK variants, in which B-cell development is blocked and antibody levels are very low. It links a defined B-cell maturation failure to recurrent bacterial infections.
Allergy : An allergy is an immune response to a usually harmless substance that causes symptoms or tissue injury. Allergy reflects an exaggerated response to particular triggers rather than broadly weakened protection.
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