WEEK TWO: Autoimmunity & Hypersensitivity (TAE) Slides 43 - 68

Question 1

Autoimmunity

Answer 1

when the body recognizes itself as foreign and attacks itself

Question 2

Autoimmune diseases

Answer 2

self tolerance is lost and immune system reacts to self

Question 3

Generally…what the immune system does when it goes right

Answer 3

• T and B cells are programmed by the THYMUS to identify self as OK
• Thymus is the organ that helps eliminate ‘self-reactive cells”
• In autoimmune diseases this doesn’t happen right

Question 4

Antigens vs antibodies

Answer 4

• An antigen is a foreign substance that enters your body
• An antibody is a protein produces by immune system
• Autoantigens, or self-antigens, are made by body to fight own cells and are usually a sign of an illness such as an autoimmune condition

Question 5

Specific antibodies (immunoglobulins)…what are they?

Answer 5

• Antibodies are also called immunoglobuins or Ig.
• They are Y-shaped proteins made by immune system’s B lymphocytes or B cells

Question 6

B-cells and specific antibodies

Answer 6

• B cells attack and eliminate viruses and other toxins outside the cell.
• They do this by making specific antibodies for a single type of antigen
• These tailored antibodies lock on to their specific antigens and tag them for attack.
• Antibodies also block these antigens, keeping them away from healthy cells
• Ultimately, antibodies kill these antigens, stopping infection

Question 7

Specific antibodies (immunoglobulins): IgG

Answer 7

IgG. These are the most abundant types of antibodies in the plasma. They detoxify harmful substances and provide long-term protection. Small, versatile, short lasting.

Question 8

Specific antibodies (immunoglobulins): IgM

Answer 8

These are the first antibodies made by B cells in response to antigens. Broad spectrum, large, stay in blood.

Question 9

Specific antibodies (immunoglobulins): IgA

Answer 9

Antiviral specific against local infections. Seen in body secretions and other body fluids such as saliva, nasal, respiratory.

Question 10

Specific antibodies (immunoglobulins): IgE

Answer 10

These antibodies trigger allergies and protect against parasites. Small amounts are in your skin, lungs, and mucosal membranes.

Question 11

Specific antibodies (immunoglobulins): IgD

Answer 11

• These antibodies bind to B cells and signal them to release IgM antibodies. - No specific functions.
• Each antibody guards against its target antigen, and many types of antibodies are found throughout the body.

Question 12

A theory of HOW autoimmune disease occur

Answer 12

• Theory of mimicry → parts of our own cells look a lot like foreign cells
• And/or the “bad” cells have adapted to look like “normal cell” and the immune system is confused
• Shirley basically said not to study these theories too much.
• Regardless of cause…autoimmune diseases injure body tissue through hypersensitivity reactions & chronic inflammation

Question 13

Hypersensitivity - what it is and how many types

Answer 13

• A normal immune response at the wrong time or excessive action
• Immune reaction that causes inflammation and destruction of healthy tissue
• 4 types

Question 14

Hypersensitivity reactions with antibodies and/or cell mediators: Type I

Answer 14

IgE → mediated immediate reaciton. Allergen associated. May be mild or severe, 15 - 30 minutes after exposure

Question 15

Hypersensitivity reactions: type II

Answer 15

Reaction to antigens on cells. 15 - 30 minutes. Antibody-mediated reaction (IgG or IgM antibodies)

Question 16

Hypersensitivity reactions: Type III

Answer 16

Immune complex-mediated reaction-persistent inflammation and destruction (SLE)
- Can be chronic and damaging

Question 17

Hypersensitivity reaction: Type IV

Answer 17

Cytotoxic, cell mediated, delayed hypersensitivity reaction (T cells instead of antibodies)

Question 18

Hypersensitivity reactions: Immediate vs delayed

Answer 18

• The 1st three types are considered immediate hypersensitivity reactions because they occur within 24 hours
• The fourth type is considered a delayed hypersensitivity reaction because it usually occurs more than 12 hours after exposure to the allergen, with a maximal reaction time between 48 and 72 hours.

Question 19

IgE hypersensitivity physiology

Answer 19

IgE is bound to mast cells via its Fc portion. When an allergen binds to these antibodies, crosslinking of IgE induces degranulation. Destroys the cell.

Question 20

IgG mediated cytotoxic hypersensitivy: physology

Answer 20

Cells are destroyed by bound antibody, either by activation of compliment or by a cytotoxic T cell with an Fc receptor for the antibody (ADCC)

Question 21

Immune Complex mediated hypersensitivity: Physiology

Answer 21

Antigen-antibody complexes are deposited in tissues, causing activation of compiment, which attracks neutrophils to site. Causes more inflammation + damage. Seen in Lupus + Rheumatoid arthritis.

Question 22

Cell mediated hypersensitivity: physiology

Answer 22

Th1 cells secrete cytokines, which activate macrophages and cytotoxic T-Cells and can cause macrophage accumulation at site.

Question 23

Systemic lupus Erythematosus

Answer 23

• Chronic, autoimmune, multi-system, inflammatory disease
• With unpredictable exacerbations and remissions
• Not a rare disease
• Effects mostly women in childbearing years - who then get older
• Especially effects non-caucasians

Question 24

Etilogy of Lupus

Answer 24

• Unknown exactly
• Possible triggers → Genetics, gender (hormones), UV light, chemicals, infectious agents and STRESS

Question 25

Pathophysiology of Lupus

Answer 25

• Production of auto-antibodies gainst own cell’s DNA
• The auto-antibodies get deposited in tissues and make inflammation and destruction
• Auto-antibodies enter cells and destroy cell DNA

Question 26

S/S of Lupus

Answer 26

1. Arthritis and arthralgias (acute or insidious pain!)
2. Skin has butterfly rash on face, hair loss, MM ulcers, patchy skin
3. Blood: anemia, and thrombocytopenia
4. Plus: Kidney, cardiac and lung damage.
5. Any cell can be affected

Question 27

Systemic Lupus erythematosus

Answer 27

-DX: Hard to diagnose
- S/S: vary so much from person to person
- Basically rule out everything else

Question 28

Treatment of Lupus

Answer 28

• Decrease inflammation so tissue destruction is reduced
• Malaria drugs are commonly used: they decrease antibody production, pain and inflammation
• used in combo with corticosteroids which decrease inflammation

Question 29

Treatment of lupus: antimalarials

Answer 29

• Examples: Chloroquine (Aralen) and hydroxychloroquine (Plaquenil) are approved for the treatment of SLE
• Have been shown to reduce the frequency of disease flares (particularly of Lupus nephritis), Maintain remission, prolong the onset of disease and reduce the risk of complications