Autoimmunity is a condition where the body's immune system mistakenly attacks its own cells, leading to various autoimmune diseases classified as organ-specific or systemic. Common examples include type 1 diabetes, systemic lupus erythematosus, and Hashimoto's thyroiditis, each with distinct effects on the body. Factors contributing to autoimmunity include hidden antigens, molecular changes in tissues, and molecular mimicry from infectious agents.

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 the immune system reacts 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.
• An organ-specific disease is one in which an immune
response is directed toward antigens in a single organ.
• Examples are Addison disease, in which autoantibodies
attack the adrenal cortex, and myasthenia gravis, in which
they attack neuromuscular cells.
• In systemic diseases the immune system attacks self
antigens in several organs.
• Systemic lupus erythematosus, for example, is
characterized by inflammation of 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 as antigens, 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
antoantobodies produced against
complement components like C2, C3 and
C4.
• The new epitopes are exposed during
complement activation and form IKs. The
IKs in serum reflects 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 antigen results in autoimmunity and tissue
damage.
• Example: Trypanosoma cruzi contain antigen that cross react with mammalian
neurons and heart muscle results in nervous and heart disease.
Rheumatic fever is 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's syndrome,
• Churg-Strauss Syndrome,
• rheumatoid arthritis (RA),

8. Type 1 diabetes mellitus
• Immune system antibodies attack and
destroy insulin-producing cells in the pancreas.
• By young adulthood, people with type 1
diabetes require insulin injections to survive.

9. Systemic lupus erythematosus (SLE)
• People with lupus develop
autoimmune antibodies that can
attach to tissues throughout the
body. The joints, lungs, blood
cells, nerves, and kidneys are
commonly affected in lupus.

10. Hashimoto’s disease
• Hashimoto’s disease is
an autoimmune
disorder that can
cause hypothyroidism,
or underactive thyroid.
• With this disease,
the immune
system attacks thyroid.
The thyroid becomes
damaged and can’t
make enough
thyroid hormones.

12. Graves' disease of the thyroid

13. Sjogren's syndrome
• 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
• is one of many forms of vasculitis.
• Vasculitis diseases are characterized
by inflammation of blood vessels.
• Churg-Strauss syndrome, in particular,
occurs in patients with a history
of asthma or allergy and features
inflammation of blood vessels (also
referred to as angiitis) in the lungs,
skin, nerves, and abdomen. The blood
vessels involved in Churg-Strauss
syndrome are small arteries and veins.

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