1' Describe the first nonspecific line of defense the body has against infection'

1
1. Describe the first non-specific line of
defense the body has against infection.

• The skin, mucous membranes, and secretions
  (saliva, tears)
• Act as
• 1. Physical barriers
• 2. Chemical defenses (sweat pH 3 5)
• - acidic stomach ?

2
2. Describe the second non-specific line of
defense, including the killer cells,
inflammatory response, and antimicrobial
proteins.

• Phagocytic WBCs (neutrophils)
• - engulf and destroy microbes
• - NK (natural killer) cells lyse infected cells
• Inflammatory response
• - increase in local blood supply
• - histamine triggers dilation (allergic
  reactions)
• - enhance migration of phagocytic cells
• Antimicrobial proteins
• - interferons limit cell to cell spread ?

3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
3. What is the importance of specific immunity?
What provides this specificity and diversity?

• Lymphocytes provide the specificity and diversity
  of the immune system
• B T cells circulate throughout the blood
  lymph
• - these recognize and respond to particular
  microbes and foreign molecules (antigens)
• B cells secrete antibodies
• With the diversity that exists, the immune system
  has the capacity to respond to millions of
  different antigenic molecules pathogens ?

8
4. How are immune responses induced, and describe
immunological memory.

• Response induced ? when antigens interact with
  specific lymphocytes
• Each selected lymphocyte is activated to divide
  differentiate, forming 2 clones of cells
• A ? effector cells to combat antigen
• B ? memory cells which bear receptors specific
  for that antigen for a long time
• - called cloning selection ?

9
(No Transcript)
10
5. How does the immune system distinguish self
from nonself? Why is this important?

• T cells are developed in the thymus
• B cells are developed in the bone marrow
• As development occurs they are tested for
  self-reactivity
• - if positive, they become nonfunctional or a
  victim to apoptosis
• Failure of self-tolerance can lead to autoimmune
  diseases like multiple sclerosis ?

11
6. Describe the various cell surface markers and
their functions.

• MHC ? major histocompatibility complex
• - marks body cells as self
• - class I ? found on all nucleated cells
• - class II ? only macrophages, B T cells
• - job is antigen presentation ? present
  antigen proteins to T cells (2 types)
• 1. Cytotoxic T cells ? antigen receptors bind to
  fragments (I MHC)
• 2. Helper T cells ? bind to fragments from II MHC
  ?

12
(No Transcript)
13
7. Describe humoral immunity and cell-mediated
immunity.

• Humoral Immunity
• Involves B cell activation and results from the
  production of antibodies that circulate in the
  blood plasma lymph

• Cell-mediated Immunity
• Depends on the action of T cells immunity to
  some infections passed along when T lymphocytes
  are transferred ?

14
(No Transcript)
15
8. Overview the function of helper T lymphocytes
in immunity.

• II MHC molecules are recognized by helper T cells
• - serve as antigen-presenting cells
• Help mobilize both humoral and cell-mediated
  branches of the immune response ?

16
9. How do cytotoxic T cells counter intracellular
pathogens? Which response is this associated with?

• Is associated with the cell-mediated response
• The T cell receptor of a cytotoxic T cell
  recognizes a class I MHC antigen complex on the
  surface of an infected cell
• Discharge of perforin protein, which lyses the
  antigen-presenting cell ?

17
10. Describe the process by which B cells make
antibodies to fight against extracellular
pathogens. Which response is this associated
with?

• Associated with the humoral response
• Response is initiated when B cells bearing
  antigen receptors are selected by specific
  antigens
• - antibody initiated to known pathogen ?

18
11. Describe antibody structure and function.

• Antibody molecule
• ? 2 identical antigen-binding sites, each
  molecule consists of four polypeptide chains (2
  light, 2 heavy) ?

19
12. Describe the antibody-mediated disposal of
antigen.

• The binding of antibodies to antigens to form
  antigen-antibody complexes is the basis of
  several antigen disposal mechanisms
• Ex neutralization (blocks viral binding sites),
  agglutination, precipitation ?

20
13. Describe the immune system in invertebrates.

• It is rudimentary and little is known
• One well-developed aspect is the distinguishing
  between self and non-self
• Have immunological memory ?

21
14. Describe the two ways in which immunity can
be achieved.

• Active ?
• Natural depends on the response of the immune
  system
• Artificial immunization/vaccines (inactivated
  toxins)
• 2. Passive ?
• Antibodies transferred from one individual to
  another
• Pregnancy or injecting antibodies from other
  people ?

22
15. Why are blood transfusions and tissue
transplants limited? Describe the problems
associated with organ transplants.

• The immune systems capacity to distinguish self
  from nonself is what limits the possibilities
• ABO blood groups, antigens, Rh factors
• Graft vs. host reaction is due to the MHC (major
  histocompatibility complex)
• The same mechanisms that help a body fight off
  invaders fights off the new transplant ?

23
16. Briefly discuss allergies.

• Allergies are hypersensitive (exaggerated)
  responses to certain environmental antigens
  (allergens)
• Most common allergies involve the antibodies of
  the IgE class (one of the 5 classes of
  Immunoglobins)
• Most serious consequence is anaphylactic shock
• - drop in blood pressure and death
• - must carry a syringe with epinephrine
• - common ? bee venom, penicillin, peanuts, fish ?

24
(No Transcript)
25
17. What are autoimmune diseases?

• When the immune system loses tolerance for self
  and turns against certain molecules of the body
• Ex lupus ? antibodies generated against all
  molecules
• Ex rheumatoid arthritis ? cartilage and joints
  are damaged
• Ex multiple sclerosis ? T cells reactive against
  myelin sheath in nervous system ?

26
(No Transcript)
27
(No Transcript)
28
18. What are immunodeficiency diseases?

• It is an immune dysfunction
• Mostly genetic, the worst is SCID (severe
  combined immunodeficiency) where both branches of
  the immune system fail
• Must have a bone marrow transplant
• Ex Hodgkins disease, suppresses the lymphatic
  system ?

29
19. Describe AIDS and the history and treatment
of this disease.

• In 1981, a particular type of sarcoma (cancer of
  skin blood vessels) was noticed ? rare except
  in immunosuppressed individuals
• AIDS ? acquired immuno-deficiency syndrome
• - susceptible to opportunistic diseases,
  infections, and cancers
• In 1983, HIV (retrovirus human immunodeficiency
  virus) was identified as the causative agent of
  AIDS
• ?

30
(No Transcript)
31
(No Transcript)
32
(No Transcript)
33
AIDS continued

• Mortality is about 100, it is the most lethal
  pathogen ever encountered
• Probably evolved from an HIV-like virus (SIV) in
  Africa
• Seen as early as 1959 in blood samples
• AIDS cannot be cured at this time and the
  progression of HIV ? AIDS cannot be stopped
• Treatment is very expensive and includes
• 1. DNA inhibitors
• 2. Reverse transcriptase inhibitors
• 3. Protease inhibitors
• HIV is transmitted via infected body fluids
  (blood/semen) is NOT contracted by casual
  contact
• In 1997, 6 million people acquired HIV ?