1. Third Line of Defense
Immune System Notes

2. LYMPHOCYTES Are the key cells of the immune system Two types: B and T
Both produced in the bone marrow
B matures in the bone marrow
T matures in the thymus

3. Immunocompetency B and T lymphocytes must recognize “self.”
“self” is determined by glycoproteins (proteins with carbohydrate side chains) on cell surface
Group of glycoproteins is called
Major Histocompatibility Complex - MHC
Genetically determined – only identical twins have perfect match
Transplants require similar matches for success (along w/antirejection drugs)

4. Immunocompetency Failure
Results in autoimmune diseases – examples
MS multiple sclerosis – myelin sheath of axons
Graves’ disease – TSH receptors –hyperthyroidism: anxiety, weight loss, etc.
Type I Diabetes – beta insulin secreting cells of the pancreas
RA rheumatoid arthritis – tissue in joints

5. ANTIGENS
B and T cells have specific antigen receptors on their plasma membranes
Antigen (def) – foreign (nonself) molecule (usually a protein) that elicits an immune response
Virus, bacteria, parasitic worm, fungus
Pollen, transplanted tissue, RBC’s, shellfish, peanuts, bee stings, snake/spider bites

6. Primary vs Secondary Immune Response
Secondary response is quicker and greater magnitude because of memory cells.

7. Third Line of Defense: Immune Response
Humoral
B lymphocytes respond to free antigens in blood
Body fluids including blood are called HUMORS; thus the name
Helper T cells stimulate both humoral and cellular
Cellular
T lymphocytes respond to antigens from cancer and virus- infected cells
Cytotoxic T cells kill/lyse
Helper T cells – orchestrate the immune system’s various responses

8. HUMORAL IMMUNITY CATEGORIES
ACTIVE
The body makes antibodies in response to antigens
PASSIVE
Immunity is passed from person to person

9. CLONAL SELECTION Produces plasma cells that produce antibodies.
Produces memory cells that activate secondary immune response.

10. ACTIVE IMMUNITY NATURAL
Acquired to exposure to antigens in daily life. Encounters with infectious diseases like measles, chicken pox, etc.
Both form Memory Cells so 2nd response is quicker and greater magnitude
ARTIFICIAL
Acquired by vaccination
Vaccines include dead, weakened, inactivated viruses, bacteria, etc. that can’t cause disease but can elicit an immune response

11. PASSIVE IMMUNITY NATURAL
Antibodies received through the placenta and after birth through breast milk
Only lasts a few months until baby begins developing own immunity
ARTIFICIAL
Antivenoms to snake, spider bites
Hepatitis A virus
Rabies virus
Injecting an antibody from someone who is already immune from a previous exposure.
Short term, but immediate protection
Treats what the body CANNOT respond to

12. AIDS Caused by HIV – Human Immunodeficiency Virus
CD4 cell surface protein on Helper T cells assist in cell-antigen-presenting-cell interactions; but are also the
Main receptor for HIV
HIV positive – body has produced antibodies
AIDS – Number of CD4’s is too low; immune system is too compromised; person dies of pneumonia, certain cancers (Kaposi’s sarcoma)

13. ALLERGIES
Hypersensitive (exaggerated) response to an environmental antigens called ALLERGENS
IgE antibodies stimulate the release of HISTAMINES from MAST CELLS results in
dilation of the blood vessels, lowering blood pressure
leaking of fluid from blood vessels leading to hives and swelling, especially around the face and throat.
asthmatic reaction -- that is, causing the lung's airways to constrict, thus making breathing very difficult

14. ANAPHYLACTIC SHOCK Occurs when the allergic reaction goes systemic
Most common causes: food allergies (peanuts and shellfish, bee/wasp stings, medications, latex
Immediate treatment – EpiPen
Injection of the hormone epinephrine (adrenaline) which reverses the symptoms by
Constricting blood vessels, opening airways
Results in increase of blood pressure, heart rate and breathing rate