A condition where elements of the immune system are defective or deficient and the individual may not be able to fight infections adequately; may be congenital (primary) or acquired (secondary).

A state in which the immune system’s ability to fight infectious disease is compromised or entirely absent.

The decreased ability of the body to fight infection and disease.

The diminished ability of the immune system to react with appropriate cellular immunity response; often the result of loss of immunoglobulins or aberrance of B- or T-cell lymphocytes.

A lack of immunity to a disease.

Abnormal condition in which some part of the body’s immune system is inadequate, and consequently resistance to infectious disease is decreased. Immunodeficiency may be congenital or acquired.

Impaired immunity resulting from inherited or acquired abnormalities of the immune system. This leads to increased vulnerability to infection. Important inherited examples of immunodeficiency are defects in function of granulocytes and the complement system. Common acquired forms of immunodeficiency are: defective function of B-type lymphocytes, and hence antibody deficiency in ‘common variable hypogamma-globulinaemia; and grossly deficient CD4 T-cell function malfunctioning T-type lymphocytes — in AIDS, secondary to HIV infection.

Decreased or compromised ability to respond to antigenic stimuli with an appropriate immune response, as the result of one or more disorders in B-cell-mediated immunity, T-cell-mediated immunity, phagocytic cells, or complement. This state may be genetic or acquired following infections, drug abuse, multiple transfusions, immunosuppressive therapy, or malnutrition. Affected patients develop chronic infections that are difficult to treat and recur frequently; these infections frequently are caused by opportunistic organisms. Other findings related to the type and degree of deficiency in the immune system include failure to thrive, thrombocytopenia, and hepatosplenomegaly. Treatments vary depending on the underlying cause. They may include combinations of antiviral agents in the acquired immunodeficiency syndrome; infusions of intravenous immune globulin (IVIG) in disorders of humoral immunity; bone marrow transplantation in patients with malignancies; and antibiotics that specifically treat active infections. Cytokine therapy and gene therapy may play a role in the treatment of patients with defined genetic defects.

The manifestation of an ailment caused by dysfunctional immune mechanisms, featuring an unusually high occurrence and swift commencement of infectious maladies.

A medical condition wherein the immune system displays inefficiency or incapacitation caused by either acquired or hereditary ailments.