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immune disorders Chronic conditions of the
IMMUNE SYSTEMthat affect the IMMUNE RESPONSEand
the body’s ability to protect and defend itself
against INFECTION. Immune disorders generally
result from a deficiency or absence of some com-
ponent or structure of immune function. Such a
deficiency may be primary, which is congenital
(present at birth), genetic (inherited), or acquired
(develops during life). People who have had their
spleen surgically removed (SPLENECTOMY) also have
reduced immune response, which results in
increased susceptibility to infection.

IMMUNE DISORDERS

AUTOIMMUNE DISORDERS COMMON VARIABLE IMMUNE
HIV/AIDS DEFICIENCY(CVID)
HYPERSENSITIVITY REACTION IMMUNOGLOBULINA (IgA)
lgA NEPHROPATHY deficiency
IgE deficiency IgM deficiency
PARTIAL COMBINED SEVERE COMBINED IMMUNODEFICIENCY
IMMUNODEFICIENCY(PCID)(SCID)
TOXIC EPIDERMAL NECROLYSIS Wegener’s granulomatosis

Frequent or chronic infection is the primary
symptom of an immune disorder other than
HYPERSENSITIVITY REACTION(allergy). BLOODtests for
immunoglobulins and antibodies generally can
diagnose immune disorders. Hypersensitivity reac-
tions generate symptoms according to the type of
reaction and may include symptoms of ALLERGIC
RHINITIS, ALLERGIC CONJUNCTIVITIS, ALLERGIC DERMATI-
TIS, orALLERGIC ASTHMA. ALLERGY TESTINGis the pre-
ferred diagnostic approach for identifying the
allergens responsible for hypersensitivity reaction,
though often a person knows the cause of an
allergy.
Immune disorders are generally chronic, which
means treatment can improve symptoms but not

cure or end the condition. Common medication

therapies for immune disorders include ANTIHISTA-

MINE MEDICATIONS, NONSTEROIDAL ANTI-INFLAMMATORY

DRUGS (NSAIDS), CORTICOSTEROID MEDICATIONS,

leukotriene receptor antagonists, MAST CELLstabi-

lizers, and DISEASE-MODIFYING RHEUMATOID DRUGS

(DMARDS). The particular medication regimen

depends on the immune disorder and the individ-

ual’s symptoms.

See also ANTIBODY; ATOPY; GENETIC DISORDERS;

IMMUNITY; IMMUNOCOMPROMISED; IMMUNODEFICIENCY;

LEUKOTRIENES; LIVING WITH IMMUNE DISORDERS.

immune response The multiple mechanisms and

processes through which the body identifies and

reacts to antigens. The immune response is the

body’s primary means of protecting itself from

INFECTION. There are three independent yet com-

plementary immune response pathways: ANTIBODY-

MEDIATED IMMUNITY (also called humoral

immunity), CELL-MEDIATED IMMUNITY, and the COM-

PLEMENT CASCADE. As well, the immune response

stimulates activity from the NERVOUS SYSTEMand

the endocrine system.

The immune response relies largely on ANTI-

BODY–ANTIGENbinding. Antigens are molecules that

identify cells to the IMMUNE SYSTEM. Antibodies are

molecules the immune system produces to bind

with nonself antigens—antigens on cells that do

not belong to the body. With antibody–antigen

binding, the antibody releases proteins called

opsonins that mark the antigen-bearing cell for

destruction by killer T-cells and natural killer (NK)

cells. Monocytes (in the BLOODcirculation) and

macrophages (in the tissues) consume the cellular

debris remaining after the marked cell’s destruc-

tion. Antibody–antigen binding also activates the

complement cascade, a biochemical response that

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