. Called also immune reaction. The immune response depends on a functioning
. These lymphocytes contribute to
production, cellular immunity, and immunologic memory.
Disorders of the Immune Response. Pathologic conditions associated with an abnormal immune response (immunopathy) may result from (1) immunodepression, that is, an absent or deficient supply of the components of either humoral or cellular immunity, or both; (2) excessive production of gamma globulins; (3) overreaction to antigens of extrinsic origin, that is, antigens from outside the body; and (4) abnormal response of the body to its own cells and tissues.
Those conditions arising from
immunosuppression include
agammaglobulinemia (absence of
gamma globulins) and
hypogammaglobulinemia (a decrease of circulating antibodies). Factors that may cause or contribute to suppression of the immune response include (1) congenital absence of the thymus or of the stem cells that are precursors of B and T lymphocytes; (2) malnutrition, in which there is a deficiency of the specific nutrients essential to the life of antibody-synthesizing cells; (3) cancer, viral infections, and extensive burns, all of which overburden the immune response mechanisms and rapidly deplete the supply of antigen-specific antibody; (4) certain drugs, including alcohol and heroin, some antibiotics, antipsychotics, and the antineoplastics used in the treatment of cancer.
Overproduction of
gamma globulins is manifested by an excessive proliferation of plasma cells (
multiple myeloma).
hypersensitivity is the result of an overreaction to substances entering the body. Examples of this kind of inappropriate immune response include
hay fever, drug and food
allergies, extrinsic
asthma,
serum sickness, and
anaphylaxis.
Autoimmune diseases are manifestations of the body's abnormal response to and inability to tolerate its own cells and tissues. For reasons not yet fully understood, the body fails to interpret its own cells as
self and, as it would with other foreign (
not-self) substances, utilizes antibodies and immunologically competent cells to destroy and contain them.