Autoimmunity

Autoimmunity is the system of immune responses of an organism against its own healthy cells and tissues. Any disease that results from such an aberrant immune response is termed an "autoimmune disease".

1. AUTOIMMUNITY
Anup Muni Bajracharya

2. Autoimmunity
•Body declares war on itself
•refers to a failure of the body’s immune system to
recognize its own cells and tissues as “self”.
•Instead, immune responses are launched against these
cells and tissues as if they were foreign or invading
bodies.
•is a condition in which the body produces antibodies and
T cell responses against elements of its own tissues
(autoantigens).
•the state in which theimmune systemreacts against the
body’s own normal components, producing disease or
functional changes.

3. Types of autoimmune diseases
•Divided into two classes:
•organ-specific and systemic.
•Anorgan-specific disease is one in which an immune
response is directed toward antigens in a single organ.
•Examples areAddison disease, in which autoantibodies
attack the adrenal cortex, andmyasthenia gravis, in which
they attack neuromuscular cells.
•Insystemic diseasesthe immune system attacks self
antigens in several organs.
•Systemic lupus erythematosus, for example, is
characterized byinflammationof the skin, joints, and
kidneys, among other organs.

4. Causes of autoimmune disease
•Antigen hidden or sequestrated in
cells or tissues
•Some body proteins remain hidden or
sequestrated from immunologically
competent cells. So, they are not
recognized as ‘self’ by the immune
system.
•When such protein escape into the
circulation (due to trauma or infection),
they behave asantigens, induce
immune response and produce tissue
damage.
•Examples:
•Lens protein:usually isolated or
sequestrated from immune system
during development. Due to trauma
to the eye, lens protein may escape
into circulation, produce autoantibody
and cause immunologic damage to
the eye (sympathetic ophthalmia).

5. Causes of autoimmune disease
•Antigen formed by molecular
changes
•Body tissues or cells undergo antigenic
alteration due to physical, chemical or
biological influences. Such neoantigen
elicit immune response.
•Examples:
•Immunoconglutinins(IKs):IKs are
antoantobodiesproduced against
complement components like C
2, C
3and
C
4.
•The new epitopes are exposed during
complement activation and form IKs. The
IKs inserumreflects the amount of
complement activation.

6. Causes of autoimmune disease
•Molecular Mimicry (Cross reacting antigen)
•Molecular mimicry or sharing of epitopes between an infectious agents or
parasites and body tissue specific antigenresultsin autoimmunity and tissue
damage.
•Example:Trypanosomacruzicontain antigen that cross react with mammalian
neurons and heart muscleresultsin nervous and heart disease.
Rheumatic feveris an inflammatory
autoimmune disease that may develop
after an infection with group A
Streptococcus bacteria (such as strep
throat or scarlet fever). The disease can
affect the heart, joints, skin, and brain.

7. Some common autoimmune disease
•80 or more different autoimmune diseases.
•long-term illnesses, with the severity of symptoms
changing over time.
•Some common autoimmune diseases include:
•diabetes mellitus type 1 (IDDM),
•systemic lupus erythematosus(SLE),
•Hashimoto's thyroiditis,
•Graves' disease of the thyroid,
•Sjogren'ssyndrome,
•Churg-Strauss Syndrome,
•rheumatoid arthritis(RA),

8. Type 1diabetes mellitus
•Immune system antibodies attack and
destroyinsulin-producing cells in thepancreas.
•By young adulthood, people withtype 1
diabetesrequireinsulininjections to survive.

9. Systemic lupus erythematosus(SLE)
•Peoplewithlupusdevelop
autoimmuneantibodiesthatcan
attachtotissuesthroughoutthe
body.Thejoints,lungs,blood
cells,nerves,andkidneysare
commonlyaffectedinlupus.

10. Hashimoto’s disease
•Hashimoto’s disease is
anautoimmune
disorderthat can
causehypothyroidism,
or underactive thyroid.
•With this disease,
theimmune
systemattacks thyroid.
The thyroid becomes
damaged and can’t
make enough
thyroidhormones.

12. Graves' disease of the thyroid

13. Sjogren'ssyndrome
•Sjogren's(SHOW-grins) syndrome is a disorder of
immune system identified by its two most common
symptoms —dry eyes and a dry mouth.

14. Churg-Strauss syndrome
•isoneofmanyformsofvasculitis.
•Vasculitisdiseasesarecharacterized
byinflammationofbloodvessels.
•Churg-Strausssyndrome,inparticular,
occursinpatientswithahistory
ofasthmaorallergyandfeatures
inflammationofbloodvessels(also
referredtoasangiitis)inthelungs,
skin,nerves,andabdomen.Theblood
vesselsinvolvedinChurg-Strauss
syndromearesmallarteriesandveins.

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