immune system, please see the overview section
“The Immune System and Allergies.”
See also ANTIBODY-MEDIATED IMMUNITY; CELL-MEDI-
ATED IMMUNITY; VIRUS.
interferons CYTOKINES(molecules on the surface
of cell membranes that direct cell activity) that
block the activity of viruses and mediate numer-
ous aspects of the IMMUNE RESPONSE. There are
more than a dozen type 1 INTERFERONS, the most
abundant of which are interferon-alpha and inter-
feron-beta. B-cell lymphocytes and T-cell lympho-
cytes produce type 1 interferons, which primarily
direct the functions of macrophages and natural
killer (NK) cells in responding to viruses. Acti-
vated T-cells produce interferon-gamma, which is
the only type 2 interferon. Interferon-gamma
helps regulate INFLAMMATION.
Interferon-alpha and interferon-beta have
strong tumor-suppression actions, which has led
to their therapeutic use for certain kinds of cancer.
Oncologists (doctors who specialize in treating
cancer) administer recombinant forms of interfer-
ons (interferons that are synthesized in a labora-
tory using RECOMBINANT DNA technology) by
injection to treat chronic myeloid LEUKEMIA, hairy
cell leukemia, malignant melanoma, and some
types of lymphoma. Doctors also use therapeutic
interferons to treat HEPATITISC and MULTIPLE SCLERO-
SIS. Pegylated interferons are synthesized to
include polyethylene glycol, which delays the rate
at which the body absorbs injected interferons.
See also B-CELL LYMPHOCYTE; CHEMOKINES; INTER-
LEUKINS; LYMPHOCYTE; LYMPHOKINES; MACROPHAGE;
NATURAL KILLER(NK) CELL; T-CELL LYMPHOCYTE; VIRUS.
interleukins CYTOKINES that influence the
growth, proliferation, and activity of leukocytes
and other BLOODcells. Leukocytes produce inter-
leukins. There are 12 major interleukins, identi-
fied as interleukin 1 (IL-1) through IL-12. Among
those significant to LEUKOCYTEdevelopment are- IL-3, which influences blood stem cell differen-
tiation into the various types of blood cells;
leukocyte differentiation into granulocytes,
monocytes, and lymphocytes; GRANULOCYTEdif-
ferentiation into basophils; and LYMPHOCYTEdif-
ferentiation into B-cell lymphocytes and T-cell
lymphocytes - IL-5, which influences leukocyte differentiation
into eosinophils - IL-7, which stimulates the BONE MARROWto pro-
duce lymphocytes
The interleukins also regulate the actions of
leukocytes—monocytes, neutrophils, basophils,
macrophages, B-cell lymphocytes, T-cell lympho-
cytes, natural killer (NK) cells, mast cells, PLASMA
cells—in the IMMUNE RESPONSE, notably the INFLAM-
MATIONprocess. The role of interleukins in the pro-
duction and activity of basophils and neutrophils,
the cells of the immune response largely responsi-
ble for inflammation, has come under scrutiny as
a key factor in the development of conditions such
as ATHEROSCLEROSIS. Research is under way to
investigate methods to manipulate interleukin
production and levels to reduce the inflammatory
response in such circumstances, thus diminishing
or eliminating the disease process. Other research
is investigating therapeutic administration of
interleukins to treat HIV/AIDS. Doctors currently
use some synthesized interleukins therapeutically
(notably IL-2) to treat certain types of cancer.
See also B-CELL LYMPHOCYTE; BLOOD STEM CELLS;
INTERFERONS; LEUKOCYTE; MACROPHAGE; MAST CELL;
MAJOR HISTOCOMPATIBILITY COMPLEX(MHC); MONOCYTE;
NATURAL KILLER(NK) CELL; T-CELL LYMPHOCYTE.278 The Immune System and Allergies