From Wikipedia, the free encyclopedia Immunology
Immunology
Immunology is a broad branch of biomedical science that primitive innate immune system, and acquired or adap-
covers the study of all aspects of the immune system tive immune system of vertebrates, the latter of which is
in all organisms.[1] It deals with the physiological func- further divided into humoral and cellular components.
tioning of the immune system in states of both health The humoral (antibody) response is defined as the
and diseases; malfunctions of the immune system in im- interaction between antibodies and antigens. Antibodies
munological disorders (autoimmune diseases, hypersen- are specific proteins released from a certain class of im-
sitivities, immune deficiency, transplant rejection); the mune cells (B lymphocytes). Antigens are defined as any-
physical, chemical and physiological characteristics of thing that elicits generation of antibodies, hence they
the components of the immune system in vitro, in situ, Antibody Gen
are Anti Generators. Immunology itself rests on an
and in vivo. Immunology has applications in several dis- understanding of the properties of these two biological
ciplines of science, and as such is further divided. entities. However, equally important is the cellular re-
sponse, which can not only kill infected cells in its own
Histological examination of the right, but is also crucial in controlling the antibody re-
sponse. Put simply, both systems are highly interdepen-
immune system dent.
In the 21st century, immunology has broadened its
Even before the concept of immunity (from immunis,
horizons with much research being performed in the
Latin for "exempt") was developed, numerous early
more specialized niches of immunology. This includes
physicians characterized organs that would later prove
the immunological function of cells, organs and systems
to be part of the immune system. The key primary lym-
not normally associated with the immune system, as well
phoid organs of the immune system are the thymus and
as the function of the immune system outside classical
bone marrow, and secondary lymphatic tissues such as
models of immunity (Yemeserach 2010).
spleen, tonsils, lymph vessels, lymph nodes, adenoids,
and skin and liver. When health conditions warrant, im-
mune system organs including the thymus, spleen, por- Clinical immunology
tions of bone marrow, lymph nodes and secondary lym- Clinical immunology is the study of diseases caused by
phatic tissues can be surgically excised for examination disorders of the immune system (failure, aberrant action,
while patients are still alive. and malignant growth of the cellular elements of the sys-
Many components of the immune system are actually tem). It also involves diseases of other systems, where
cellular in nature and not associated with any specific or- immune reactions play a part in the pathology and clini-
gan but rather are embedded or circulating in various tis- cal features.
sues located throughout the body. The diseases caused by disorders of the immune sys-
tem fall into two broad categories: immunodeficiency,
Classical immunology in which parts of the immune system fail to provide an
adequate response (examples include chronic granulo-
Classical immunology ties in with the fields of epidemi-
matous disease), and autoimmunity, in which the im-
ology and medicine. It studies the relationship between
mune system attacks its own host’s body (examples in-
the body systems, pathogens, and immunity. The earliest
clude systemic lupus erythematosus, rheumatoid arthri-
written mention of immunity can be traced back to the
tis, Hashimoto’s disease and myasthenia gravis). Other
plague of Athens in 430 BCE. Thucydides noted that peo-
immune system disorders include different hypersensi-
ple who had recovered from a previous bout of the dis-
tivities, in which the system responds inappropriately to
ease could nurse the sick without contracting the illness
harmless compounds (asthma and other allergies) or re-
a second time. Many other ancient societies have refer-
sponds too intensely.
ences to this phenomenon, but it was not until the 19th
The most well-known disease that affects the im-
and 20th centuries before the concept developed into sci-
mune system itself is AIDS, caused by [HIV. AIDS is an
entific theory.
immunodeficiency characterized by the lack of CD4+
The study of the molecular and cellular components
("helper") T cells and macrophages, which are destroyed
that comprise the immune system, including their func-
by HIV.
tion and interaction, is the central science of immunol-
ogy. The immune system has been divided into a more
1
From Wikipedia, the free encyclopedia Immunology
Clinical immunologists also study ways to prevent tibody for a particular antigen before being exposed to
transplant rejection, in which the immune system at- the antigen itself then the child will produce a damp-
tempts to destroy allografts os ened response. Passively acquired maternal antibodies
can suppress the antibody response to active immuniza-
Developmental immunology tion. Similarly the response of T-cells to vaccination dif-
fers in children compared to adults, and vaccines that in-
The body’s capability to react to antigen depends on a duce Th1 responses in adults do not readily elicit these
person’s age, antigen type, maternal factors and the area same responses in neonates.[3] By 6-9 months after birth,
where the antigen is presented.[2] Neonates are said to a child’s immune system begins to respond more strong-
be in a state of physiological immunodeficiency, because ly to glycoproteins. Not until 12-24 months of age is there
both their innate and adaptive immunological responses a marked improvement in the body’s response to poly-
are greatly suppressed. Once born, a child’s immune sys- saccharides. This can be the reason for the specific time
tem responds favorably to protein antigens while not as frames found in vaccination schedules.[4][5]
well to glycoproteins and polysaccharides. In fact, many During adolescence the human body undergoes sev-
of the infections acquired by neonates are caused by low eral physical, physiological and immunological changes.
virulence organisms like Staphylococcus and Pseu- These changes are started and mediated by different hor-
domonas. In neonates, opsonic activity and the ability to mones. Depending on the sex either testosterone or 17-β-
activate the complement cascade is very limited. For ex- oestradiol, act on male and female bodies accordingly,
ample, the mean level of C3 in a newborn is approximate- start acting at ages of 12 and 10 years.[6]
ly 65% of that found in the adult. Phagocytic activity is There is evidence that these steroids act directly not
also greatly impaired in newborns. This is due to low- only on the primary and secondary sexual characteris-
er opsonic activity, as well as diminished up-regulation tics, but also have an effect on the development and reg-
of integrin and selectin receptors, which limit the abili- ulation of the immune system.[7]
ty of neutrophils to interact with adhesion molecules in There is an increased risk in developing autoimmu-
the endothelium. Their monocytes are slow and have a nity for pubescent and post pubescent females and
reduced ATP production, which also limits the newborns males.[8] There is also some evidence that cell surface re-
phagocytic activity. Although, the number of total lym- ceptors on B cells and macrophages may detect sex hor-
phocytes is significantly higher than in adults, the cellu- mones in the system.[9]
lar and humoral immunity is also impaired. Antigen pre- The female sex hormone 17-β-oestradiol has been
senting cells in newborns have a reduced capability to ac- shown to regulate the level of immunological re-
tivate T cells. Also, T cells of a newborn proliferate poor- sponse.[10] Similarly, some male androgens, like testos-
ly and produce very small amounts of cytokines like IL-2, terone, seem to suppress the stress response to infection;
IL-4, IL-5, IL-12, and IFN-g which limits their capacity to but other androgens like DHEA have the opposite effect,
activate the humoral response as well as the phagocitic as it increases the immune response instead of down
activity of macrophage. B cells develop early in gestation playing it.[11] As in females, the male sex hormones seem
but are not fully active.[3] to have more control of the immune system during pu-
berty and the time right after than in fully developed
adults. Other than hormonal changes physical changes
like the involution of the Thymus during puberty will al-
so affect the immunological response of the subject or
patient.[12]
Immunotherapy
Monocytes: An Artist’s Impression Main article: Immunotherapy
The use of immune system components to treat a disease
Maternal factors also play a role in the body’s im- or disorder is known as immunotherapy. Immunothera-
mune response. At birth most of the immunoglobulin is py is most commonly used in the context of the treat-
present is maternal IgG. Because IgM, IgD, IgE and IgA ment of cancers together with chemotherapy (drugs) and
don’t cross the placenta, they are almost undetectable at radiotherapy (radiation). However, immunotherapy is al-
birth. Although some IgA is provided in breast milk. Th- so often used in the immunosuppressed (such as HIV pa-
ese passively acquired antibodies can protect the new- tients) and people suffering from other immune deficien-
born up to 18 months, but their response is usually short- cies or autoimmune diseases.
lived and of low affinity.[3] These antibodies can also pro-
duce a negative response. If a child is exposed to the an-
2
From Wikipedia, the free encyclopedia Immunology
Diagnostic immunology According to the American Academy of Allergy, Asthma,
and Immunology (AAAAI), "an immunologist is a re-
Main article: Diagnostic immunology search scientist who investigates the immune system of
The specificity of the bond between antibody and antigen vertebrates (including the human immune system). Im-
has made it an excellent tool in the detection of sub- munologists include research scientists (Ph.D.) who work
stances in a variety of diagnostic techniques. Antibodies in laboratories. Immunologists also include physicians
specific for a desired antigen can be conjugated with a ra- who, for example, treat patients with immune system
diolabel, fluorescent label, or color-forming enzyme and disorders. Some immunologists are physician-scientists
are used as a "probe" to detect it. However, the similarity who combine laboratory research with patient care." [14]
between some antigens can lead to false positives and
other errors in such tests by antibodies cross-reacting
with antigens that aren’t exact matches.[13]
See also
• Outline of immunology
Evolutionary immunology •
•
List of immunologists
Immunomics
Study of the immune system in extant species is capable • History of immunology
of giving us a key understanding of the evolution of • Osteoimmunology
species and the immune system. • International Reviews of Immunology
A development of complexity of the immune system
can be seen from simple phagocytotic protection of sin-
gle celled organisms, to circulating antimicrobial pep-
References
tides in insects to lymphoid organs in vertebrates. How- [1] Janeway’s Immunobiology textbook Searchable
ever, it is important to recognize that every organism liv- free online version at the National Center for
ing today has an immune system that has evolved to be Biotechnology Information
absolutely capable of protecting it from most forms of [2] Goldsby RA, Kindt TK, Osborne BA and Kuby J
harm; those organisms that did not adapt their immune (2003). Immunology (5th ed.). San Francisco: W.H.
systems to external threats are no longer around to be Freeman. ISBN 0-7167-4947-5.
observed. [3] ^ Jaspan HB, Lawn SD, Safrit JT, Bekker LG
Insects and other arthropods, while not possessing (February 2006). "The maturing immune system:
true adaptive immunity, show highly evolved systems of implications for development and testing HIV-1
innate immunity, and are additionally protected from ex- vaccines for children and adolescents". AIDS 20 (4):
ternal injury (and exposure to pathogens) by their chiti- 483–94. doi:10.1097/01.aids.0000210602.40267.60.
nous shells. PMID 16470112.
[4] Glezen WP (December 2001). "Maternal vaccines".
Reproductive immunology Prim. Care 28 (4): 791–806, vi–vii. doi:10.1016/
S0095-4543(05)70041-5. PMID 11739030.
Main article: Reproductive immunology [5] Holt PG, Macaubas C, Cooper D, Nelson DJ,
This area of the immunology is devoted to the study of McWilliam AS (1997). "Th-1/Th-2 switch regulation
immunological aspects of the reproductive process in- in immune responses to inhaled antigens. Role of
cluding fetus acceptance. The term has also been used dendritic cells in the aetiology of allergic
by fertility clinics to address fertility problems, recurrent 417:
respiratory disease". Adv. Exp. Med. Biol. 417 301–6.
miscarriages, premature deliveries, and dangerous com- PMID 9286377.
plications such as pre-eclampsia. [6] Sizonenko PC, Paunier L (November 1975).
"Hormonal changes in puberty III: Correlation of
Immunologist plasma dehydroepiandrosterone, testosterone,
FSH, and LH with stages of puberty and bone age in
Immunologist normal boys and girls and in patients with
Occupation Addison’s disease or hypogonadism or with
Activity Science, Laboratory, Medicine premature or late adrenarche". J. Clin. Endocrinol.
sectors Metab. 41 (5): 894–904. doi:10.1210/jcem-41-5-894.
PMID 127002.
Description
[7] Verthelyi D (June 2001). "Sex hormones as
Education Doctor of Philosophy, Doctor of Medicine, immunomodulators in health and disease". Int.
required Doctor of Osteopathic Medicine Immunopharmacol. 1 (6): 983–93. doi:10.1016/
S1567-5769(01)00044-3. PMID 11407317.
3
From Wikipedia, the free encyclopedia Immunology
[8] Stimson WH (September 1988). "Oestrogen and molecules in immunoassays". Clin. Chem. 37 (2):
human T lymphocytes: presence of specific 144–53. PMID 1993317.
receptors in the T-suppressor/cytotoxic subset". [14] "Office of Science Education - LifeWorks -
Scand. J. Immunol. 28 (3): 345–50. doi:10.1111/ Immunologist". http://science.education.nih.gov/
j.1365-3083.1988.tb01459.x. PMID 2973658. LifeWorks.nsf/Alphabetical+List/Immunologist.
[9] Benten WP, Stephan C, Wunderlich F (June 2002). Retrieved 2009-09-10.
"B cells express intracellular but not surface
receptors for testosterone and estradiol". Steroids
67 (7): 647–54. doi:10.1016/S0039-128X(02)00013-2.
External links
PMID 11996938. • The Immunology Link, a rich resource for
[10] Beagley KW, Gockel CM (August 2003). "Regulation Immunology information
of innate and adaptive immunity by the female sex • American Academy of Allergy, Asthma &
hormones oestradiol and progesterone". FEMS Immunology
Immunol. Med. Microbiol. 38 (1): 13–22. doi:10.1016/ • British Society for Immunology
S0928-8244(03)00202-5. PMID 12900050. • Annual Review of Immunology (journal)
[11] Kanda N, Tamaki K (February 1999). "Estrogen • BMC: Immunology- BioMed Central:Immunology is
enhances immunoglobulin production by human an open access journal publishing original peer-
PBMCs". J. Allergy Clin. Immunol. 103 (2 Pt 1): 282–8. reviewed research articles.
doi:10.1016/S0091-6749(99)70503-8. PMID 9949320. • journal home Nature Reviews Immunology
[12] McFarland RD, Douek DC, Koup RA, Picker LJ (April • The Immunology Database and Analysis Portal - an
2000). "Identification of a human recent thymic NIAID-funded database resource of reference and
emigrant phenotype". Proc. Natl. Acad. Sci. U.S.A. 97 experiment data covering the entire immunology
(8): 4215–20. doi:10.1073/pnas.070061597. domain
PMC 18202. PMID 10737767. • Current discussions on Immunology in a scientific
http://www.pubmedcentral.nih.gov/ community
articlerender.fcgi?tool=pmcentrez&artid=18202. • The Center for Modeling Immunity to Enteric
[13] Miller JJ, Valdes R (February 1991). "Approaches to Pathogens (MIEP)
minimizing interference by cross-reacting
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Categories:
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