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Bio 103
Lake Tahoe Community College
Winter Quarter
Instructor: Sue Kloss
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Chapter 43: The Immune System
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I. Nonspecific Defenses Against Infections
A. Nonspecific defenses (innate immunity)
1. Body’s first line of defense - nonspecific
B. Internal cellular defenses
1. microbes that get past all these defenses
2. These are found in interstitial fluids as well as blood vessels.
3. Neutrophils
4. eosinophils
C. Other nonspecific defenses
1. when a cell is invaded by a virus
2. interferons
3. recombinant DNA technology
4. complement proteins
D. natural killer cells
E. Inflammatory response mobilizes nonspecific defense forces
1. inflammatory response is a major component of nonspecific defense
2. any damage to tissue, whether microbes or injury related, even an insect bite, triggers it
3. mosquito bite:
4. Inflammatory response
5. inflammatory response can be local or systemic
F. The lymphatic system becomes a crucial battleground during infection
1. lymph system is involved in both specific and nonspecific resistance
2. lymphatic system
3. lymph is similar to interstitial fluids
4. lymph system functions:
5. 1% of fluids that leave capillary
6. lymphatic vessels take up fluid from tissue spaces in the skin
7. fluid enters the lymphatic system
8. 2 large lymphatic veins
9. lymphatic vessels resemble veins
10. infection fighting activities of the lymph
11. lymph circulates, carrying microbes and sometimes cancer cells.
12. When you are fighting infection, your lymph system becomes major battleground
13. lymph nodes become swollen and tender
II. Specific or acquired immunity
A. Immune response counters specific invaders
1. If our nonspecific defenses fail to ward off infection, our immune system provides another line of
defense.
2. Our immune system recognizes and defends against invading microbes and against cancer cells
3. our immune system acts more efficiently than nonspecific response
4. It can also amplify some nonspecific responses
5. Nonspecific defenses are always ready
6. when immune system detects an antigen
7. antigen = molecule that elicits an immune response (antibody generating)
8. antigens can be certain molecules
9. an antibody is a protein
10. immune system has “memory”
11. will kill invader organisms
12. immune system is adaptive
13. immunity = resistance to specific invaders
14. active immunity
15. passive immunity
16. passive immunity is temporary
B. Antigen Recognition by Lymphocytes
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1. lymphocytes- wbcs
2. lymphocytes produce the immune response
3. like all blood cells, lymphocytes originate from stem cells in bone marrow
4. some lymphocytes remain in bone marrow
5. T cells
6. B and T cells work together
7. B cells secrete antibodies
8. immunity conferred by T cells is cell-mediated immunity
9. When a T cell develops in thymus or B cell develops in bone marrow
C. Generation of lymphocyte diversity by Gene Rearrangement in B cells
1. Secquence of amino acids in a V part of the chain
2. recombinase
3. chain
4. V-J rearrangement
D. Testing and removal
1. rearrangement of the antigen receptors is random
2. B and T cells mature in the bone marrow and Thymus
3. developing T cells are tested against class I and class II MHC molecules
4. lymphocytes bearing receptors specific for your bodys molecules
5. self tolerance
6. failure of self tolerance
E. Clonal selection of lymphocytes
1. soluble antigens or antigens present on surface of microbe, infected body cell or cancer cell
2. selection of B cell or T cell by an antigen
4. CLONAL SELECTION IS: EACH ANTIGEN BINDS TO SPECIFEC RECEPTORS,
SELECTIVELY ACTIVATES A TINYFRACTION OF THE BODY’S DIVERSE POOL OF LYMPHOCYTES.
THIS RELATIVELY SMALL NUMBER OF SELECTED CELLS GIVES RISE TO CLONES OF THOUSANDS
OF CELLS, ALL SPECIFIC FOR AND DEDICATED TO ELIMINATING THAT ANTIGEN
5. primary immune response
6. secondary immune response
7. immune systems capac ity to generate secondary immune response
III. B Cells confer Humoral Immunity and T cells confer cell mediated immunity
A. intro
1. Humoral immunity
2. cell mediated immune response
3. Helper T
B. Helper T cells: a response to nearly all antigens
1. helper T cell encounters and recognizes a class II MHC molecule
2. helper Ts have a surface protein called CD4
3. activated helper Ts secrete cytokines
4. Class II MHC molecules recognized by helper Ts
C. Cytotoxic T Cells - response to infected cells and cancer cells
1. cytotoxic Ts2. Tumor cells carry tumor antigens not found on normal body cells
D. B Cells - response to extracellular pathogens
1. antigens
2. B cells
3. B cell proliferates into a clone
4. When antigen binds to B cell, it takes in some of the antigen
5. Most antigens recognized by B cells contain multiple epitopes,
6. all plasma cells in one clone produce antibodies
7. each plasma cell secretes ~2000 antibodies /sec
E. Antibody mediated disposal of antigens
1. Main role of antibodies in eliminating invading microbes
2. B cells are the primary defenders in humoral immunity
3. primary response of humoral immunity - (initial encounter with antigen)
4, secondary response of humoral immunity 5. Main role of antibodies in eliminating invading microbes is to mark the invaders
F. T cells mount cell mediated defense and aid humoral immunity
1. B cells work against invaders in the blood, interstitial fluids and lymph
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2. many invaders, including viruses, enter cells and reproduce there.
3. Cell mediated immunity (T cells) battles pathogens inside body cells
4. T cells respond only to antigens present on the surfaces of the body’s own cells
5. 2 kinds of T cells
6. Helper T cells have many roles in immunity
7. Helper Ts interact with other wbcs that become antigen- presenting cells (APCs)
F. Cytotoxic T cells may help prevent cancer
1. people with immune deficiencies
2. Our immune system has self proteins
F. Malfunction or failure of immune system can cause disease.
1. autoimmmune diseases - immune system turns against the body’s own molecules.
2. immunodeficiency disease - lack one or more components of normal immune system.
3. Physical and emotional stress may also weaken the immune system
4. Allergies are overreactions to environmental antigens - abnormal sensitivities to antigens in
surroundings
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1. Explain what is meant by nonspecific defense and list the nonspecific lines of defense in the vertebrate body.
2. Distinguish between:
a. innate and acquired immunity
b. humoral and cell mediated response
3. Explain how the physical barrier of skin is reinforced by chemical defenses.
4. Define phagocytosis. Name four types of phagocytic leukocytes.
5. Explain how interferon limits cell-to-cell spread of viruses.
6. Describe the inflammation response, including how it is triggered.
7. Describe the factors that influence phagocytosis during the inflammation response.
8. Explain how the action of natural killer cells differs from the action of phagocytes.
9. Explain what occurs during the condition known as septic shock.
10. Describe the roles of antimicrobial proteins in innate immunity.
11. Distinguish between antigens and antibodies.
12. Distinguish between antigen and epitope.
13. Explain how B lymphocytes and T lymphocytes recognize specific antigens
14. Explain how the particular structure of a lymphocyte’s antigen binding site forms during development. Explain the role of
recombinase in generating the staggering variability of lymphocytes.
15. Explain why the antigen receptors of lymphocytes are tested for self-reactivity during development. Predict the consequences
that would occur if such testing did not take place.
16. Describe the mechanism of clonal selection. Distinguish between effector cells and memory cells.
17. Distinguish between primary and secondary immune responses.
18. Describe the cellular basis for immunological memory.
20. Compare the structures and functions of cytotoxic T cells and helper T cells.
21. Compare the production and functions of class I MHC and class II MHC molecules.
22. Distinguish between humoral immunity and cell-mediated immunity.
23. Describe the roles of helper T lymphocytes in both humoral and cell-mediated immunity.
24. Assemble a table correctly relating the following terms: Helper Ts and Cytotoxic Ts, MHC Class I and Class II, proteins CD4
and CD8. Note on your table which types of cells are recognized by Cytotoxic vs Helper Ts.
25. Explain how cytotoxic T cells and natural killer cells defend against tumors.
26. Explain why macrophages are regarded as the main antigen-presenting cells in the primary response but memory B cells are
the main antigen-presenting cells in the secondary response.
27. Diagram and label the structure of an antibody and explain how this structure allows antibodies to (a) recognize and bind to
antigens, and (b) assist in the destruction and elimination of antigens.
28. Distinguish between the variable (V) and constant (C) regions of an antibody molecule.
29. Describe the production and uses of monoclonal antibodies.
30. Compare the processes of neutralization, opsonization, and agglutination. Describe the importance of, and how complement
proteins work in destroying affected cells.
31. Distinguish between active and passive immunity and describe examples of each.
32. Describe the infectious agent that causes AIDS and explain how it enters a susceptible cell. Note strategies that can reduce a
person’s risk of infection.
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