1. Chapter 43 ~
The Immune System
The 3 R’s- Reconnaissance,
Recognition and Response

2. Types of Immunity
Innate Defense – nonspecific barriers (skin, mucus) and chemical defenses
phagocytic cells
Acquired Defense- highly specific, only after exposure to the pathogen
Specific immunity includes lymphocytes and antibodies
Macrophage filled
with pathogens

3. Lines of Defense- Nonspecific or Specific

4. Non-specific patrolling cells
bacteria
attack pathogens, but don’t “remember” for next time
leukocytes
phagocytic white blood cells
macrophages, neutrophils, natural killer cells, dendritic cells
Antimicrobial proteins
Complement system
Interferons
inflammatory response
increase in body temp.
increase capillary permeability
attract macrophages/neutrophils
macrophage
yeast

5. Specific defense Antigens illicit a response of B or T cells
Lymphocytes recognize a small portion of the antigen called an epitope
After initial response- possible illness
Selected B cells clone themselves to become antibodies
Some B cell clones develop into memory cells

6. The Inflammatory Response
1- Tissue injury causes release of chemical signals
2. Histamine causes dilation and increased permeability of capillaries
3. Increased blood flow causes heat and swelling
cytokines secreted by blood vessel endothelial cells initiate phagocytic migration of WBCs
4- Phagocytosis of pathogens occurs by WBCs

7. Acquired or Specific Immunity Terms
B Cells- WBCs made in bone marrow
T Cells WBC stored in thymus
Antigen: a foreign molecule that elicits a response by lymphocytes
Antibodies: antigen-binding immunoglobulin, produced by B cells
Antigen receptors: plasma membrane receptors on B and T cells
Memory cells: cloned lymphocytes

8. Major Histocompatability Complex MHC
body cell surface antigens coded by a family of genes
Allows cells to recognize each other as SELF
Different antigens will be considered FOREIGN

9. Cell-mediated Response: T cells
Cytotoxic T cells
Destroy cells infected by intracellular pathogens and cancer cells by cell lysis by the chemical perforin

10. Humoral response: B cells
Occurs outside the cell
Helper T cell aids macrophage with CD4 protein
Activated T cell secretes cytokines that activate B cell
B cell differentiates into memory and plasma cells (antibodies)

11. Helper T lymphocytes Function in both humoral & cell-mediated immunity
Stimulated by antigens
Clones itself and produces memory cells

12. How Antibodies work antibody binds to and blocks antigen activity
Agglutination: antigen clumping
Precipitation: cross-linking of soluble antigens
Complement fixation: activation of 20 serum proteins, that lyse viruses and pathogenic cells

13. Primary and Secondary Immune Responses
Primary Secondary
-lag time of 10 days -no lag time
to 14 days as body antibodies already
makes antibodies made
- response is
immediate

14. Immunity in Health & Disease
Active immunity:
natural: recovering from disease
artificial: immunization
Passive immunity:
natural: mother to fetus; breast milk
• artificial: rabies antibodies

15. Active Immunity Get exposed to pathogen! Naturally – get sick
Artificially – get a vaccination
Both methods cause memory cells to be made for future exposures.
Rapid response to second exposure. You don’t even know you were exposed!

16. Passive immunity Naturally obtaining antibodies from mother
antibodies pass from mother to baby across placenta or in mother’s milk
Artificially
injection of antibodies
Ex: anti-venom serum
short-term immunity

17. Tissue Graft and Organ Transplantation
Can be a problem due to MHC
Antirejection drugs are used to prevent tissue or organ rejection
Identical twins have identical MHC but can have different antibodies (they aren’t always in the same place)
In 2013 a 3 year old has a 5 organ transplant-
liver, stomach, pancreas small and large
intestine

18. Abnormal immune functions
Allergies hypersensitive responses to environmental antigens (allergens);
Autoimmune disease (generate antibodies against own cells):
-multiple sclerosis (myelin sheath of nerve cells)
-lupus (variety of cells)
-rheumatoid arthritis (joints)
-insulin-dependent diabetes mellitus (pancreatic cells)
Immunodeficiency diseases:
- inborn -SCIDS (bubble-boy)
- acquired -AIDS

19. Acquired ImmunoDeficiency Syndrome
Immune system is susceptible to opportunistic infections ( a fungal pneumonia, Kaposi’s sarcoma)
Loss of helper T cells
HIV is highly mutable
Transmission requires transfer of body fluids (semen and blood)

20. How Do Vaccines Work? Vaccines imitate an infection
Immune system will respond by producing T cells and antibodies