adapative immunity pt2. pt.4

What is an immunodeficiency?

A congenital or acquired condition in which the production or function of immune cells, phagocytes, or complement is abnormal.

What are the two types of immunodeficiencies

• Congenital (present at birth)

• Acquired (develop later)

What causes Severe Combined Immunodeficiency (SCID)?

Genetic defects causing deficiencies of both B cells and T cells.

Why is SCID called "combined" immunodeficiency?

Because both B cells and T cells are deficient.

What is Hodgkin's disease?

Cancer of the lymph nodes that causes an acquired immunodeficiency.

What does AIDS stand for?

Acquired Immune Deficiency Syndrome.

: What virus causes AIDS?

HIV (Human Immunodeficiency Virus).

Which immune cells does HIV primarily attack?

: Helper T cells (CD4 cells).

Which HIV glycoprotein binds to CD4 cells

gp120.

What is the function of gp41?

Helps HIV fuse with and enter the host cell.

What enzyme does HIV use to make DNA from viral RNA?

Reverse transcriptase.

What is a provirus?

The viral DNA copy that inserts into the host cell's DNA.

What does the provirus do?

Directs the host cell to produce more HIV.

What type of drugs inhibit reverse transcriptase?

Reverse transcriptase inhibitors (such as AZT).

What type of drugs inhibit HIV protease?

Protease inhibitors (such as saquinavir).

What is an autoimmune disease?

A disease in which the immune system attacks the body's own tissues.

Which immune cells are involved in autoimmune diseases?

• Autoantibodies

• Cytotoxic T cells

What does Multiple Sclerosis (MS) affect?

White matter of the brain and spinal cord.

What does Myasthenia Gravis affect?

Communication between nerves and skeletal muscles.

What does Graves' disease cause?

Excessive production of thyroxine by the thyroid gland.

What happens in Type I Diabetes Mellitus?

Destruction of pancreatic beta cells, causing insulin deficiency

Which cells are destroyed in Type I Diabetes?

A: Pancreatic beta cells.

What organs are affected by Systemic Lupus Erythematosus (SLE)?

• Kidneys

• Heart

• Lungs

• Skin

What is glomerulonephritis?

Severe impairment of kidney (renal) function.

What is rheumatoid arthritis (RA)?

An autoimmune disease that systematically destroys joints

How is rheumatoid arthritis treated?

• Suppress the immune response

• Anti-CD4 antibodies

• Thalidomide (decreases TNF-α)

What is TNF-α (tumor necrosis factor-alpha)?

An inflammatory cytokine produced by lymphocytes and especially macrophages.

What are the functions of TNF-α?

• Enhances nonspecific killing

• Slows tumor growth

• Damages blood vessels

• Increases granulocyte chemotaxis

• Activates T cells, phagocytes, and eosinophils

What are three possible triggers of autoimmune disease?

1. Ineffective negative selection

2. New self-antigens appear

3. Foreign antigens resemble self-antigens (molecular mimicry)

What is molecular mimicry?

A: Foreign antigens resemble self-antigens, causing the immune system to attack the body's own tissues.

Give an example of molecular mimicry.

Streptococcal antibodies cross-react with heart tissue, causing rheumatic fever.

What is a hypersensitivity?

An exaggerated immune response that causes tissue damage.

What are allergy-causing antigens called?

Allergens

How are hypersensitivity reactions classified?

By their time course and whether antibodies or T cells are involved.

: What is Type I hypersensitivity?

Immediate, antibody-mediated hypersensitivity that begins within seconds.

Which antibody is responsible for Type I hypersensitivity?

IgE

Which cells does IgE bind?

Mast cells and basophils.

What chemical is released by mast cells during an allergic reaction?

Histamine.

What is anaphylaxis?

A severe immediate allergic reaction caused by allergen-induced IgE activation.

How is anaphylaxis treated?

Antihistamines

What is anaphylactic shock?

A life-threatening systemic allergic reaction with bronchoconstriction, edema, and circulatory shock

How is anaphylactic shock treated?

Epinephrine

What is atopy?

A genetic tendency to develop immediate allergies such as hay fever, hives, or asthma

What is Type II hypersensitivity?

Cytotoxic antibody-mediated reaction against body cells.

Give an example of Type II hypersensitivity.

mismatched blood transfusion

What is Type III hypersensitivity?

Immune complexes form and become trapped, causing inflammation and tissue damage.

Give an example of Type III hypersensitivity.

farmer lung

What is Type IV hypersensitivity?

Delayed, T-cell-mediated hypersensitivity that appears 1–3 days after exposure.

Which cells mediate Type IV hypersensitivity?

• Cytotoxic T cells

• Delayed hypersensitivity T cells (TDH)

How is Type IV hypersensitivity treated?

Corticosteroids

Give two examples of Type IV hypersensitivity.

• Allergic contact dermatitis

• Tuberculosis (TB) skin test