1. Memmler’s The Human Body in Health and Disease 11th edition
Chapter 17
Body Defenses, Immunity, and Vaccines

2. The Immune System Types of general body defenses against disease
Nonspecific defenses
Effective against any harmful agent
present from birth; do not distinguish one type of threat from another
Specific defenses
Effective against a certain agent only
Depend on specific lymphocyte activities
Produce state of protection (immunity or specific resistance)

3. Why Do Infections Occur?
Factors involved in infection
Portal of entry
Virulence of organism
Aggressiveness
Toxin production
Dose (number) of pathogens
Individual condition (predisposition) to infection

4. Nonspecific Defenses Physical barriers Phagocytes
NK Cells (immunological surveillance)
Inflammatory response
Fever
Interferons
Complement

5. Chemical and Mechanical Barriers
Skin
Mucous membranes
Cilia
Body secretions
Tears
Perspiration
Saliva
Digestive juices
Reflexes
Sneezing
Coughing
Vomiting
Diarrhea

6. Phagocytes Engulf and destroy foreign compounds and pathogens
“First line of cellular defense” against pathogenic invasion
Types
Neutrophils (in bloodstream and tissues)
Phagocytize cellular debris or bacteria
Eosinophils (less abundant)
Phagocytize foreign compounds and antibody-coated pathogens
Macrophages (derived from monocytes)
Fixed (permanent residents of certain organs)
Free (travel throughout body)

7. Figure Physical barriers prevent pathogens and toxins from entering body tissues and phagocytes provide the next line of defense 7

8. Natural Killer Cells Type of lymphocyte
Can recognize body cells with abnormal membranes
Found in lymph nodes, spleen, bone marrow, blood
Secrete protein that breaks down cell membrane

9. Immunological Surveillance
Constant monitoring of normal tissues by NK cells
Normal cells are generally ignored by immune system
Cancer cells often contain tumor-specific antigens
NK cells recognize as abnormal and destroy
NK cells recognize bacteria, foreign cells, virus- infected cells, and cancer cells

10. NK cells recognize and kill target cells interaction of perforin
Step 1: If a cell has
unusual components in its
plasma membrane, an NK
cell recognizes that other
cell as abnormal. Such
recognition activates the
NK cell, which then
adheres to its target cell.
Step 2: The Golgi apparatus
moves around the nucleus until
the maturing face points directly
toward the abnormal cell. A flood
of secretory vesicles is then
produced at the Golgi apparatus.
These vesicles, which contain
proteins called perforins, travel
through the cytoplasm toward the
cell surface.
Step 3: The perforins
are released at the cell
surface by exocytosis
and diffuse across the
narrow gap separating
the NK cell from its
target.
Step 4: As a result of the
pores made of perforin
molecules, the target cell
can no longer maintain
its internal environment,
and it quickly
disintegrates.
Golgi apparatus
NK cell
Abnormal
cell
Figure NK cells perform immunological surveillance, detecting and destroying abnormal cells
Perforin
molecules
Pores produced by the
interaction of perforin
molecules
NK cell
Abnormal
cell 10

11. Immunological Surveillance, cont’d
NK cells also destroy abnormal cells
Abnormal daughter cells occur during cell division
Some abnormal cells become cancer cells

12. destroys abnormal cell
NK cells detect and destroy abnormal cells
resulting from faulty cell division
NK cell identifies and
destroys abnormal cell
Abnormal cell
Stem cell
Figure NK cells perform immunological surveillance, detecting and destroying abnormal cells
Daughter cells
Daughter cells 12

13. Inflammation Infection is inflammation caused by pathogens
Inflammatory reaction (response)
Heat, redness, swelling, pain
Cells release histamine
Leukocytes enter tissue
Granulocytes, macrophages, mast cells
Leukocytes and plasma produce inflammatory exudate
Pus is produced
Lymph nodes enlarge

14. The Events in Inflammation
Tissue damage causes chemical change in interstitial fluid
Mast cell activation
Release of histamine and heparin
Causes:
Increased blood flow to area
Clot formation
Phagocyte attraction (removes debris and activates specific defenses)
Tissue repair
Pathogen removal, clot erosion, scar tissue formation

15. Fever
As phagocytes work, they release substances that raise body temperature
Pyrogens
Reset temperature thermostat in hypothalamus
Stimulates phagocytes
Increases metabolic rate which may accelerate tissue defenses and repair process
Decreases some organisms’ ability to multiply

16. Interferons
Small proteins released by activated lymphocytes, macrophages, and virus-infected tissues
Trigger antiviral proteins in cytoplasm of nearby cells
Do not prevent entry of viruses but interfere with viral replication
Also stimulate activities of macrophages and NK cells

17. Interferons, cont’d Three types
Alpha (α) interferons (produced by virus- infected cells)
Attract and stimulate NK cells and give viral resistance
Beta (β) interferons (secreted by fibroblasts)
Slow inflammation in damaged area
Gamma (γ) interferons (secreted by T cells and NK cells)
Stimulate macrophage activity

18. Three Types of Interferons
Alpha (α)-interferons
are produced by cells
infected with viruses.
They attract and
stimulate NK cells and
enhance resistance to
viral infection.
Beta (β)-interferons,
secreted by fibroblasts,
slow inflammation in a
damaged area.
Figure Interferons and the complement system are distributed widely in body fluids
Gamma
()-interferons,
secreted by T cells and
NK cells, stimulate
macrophage activity. 18

19. Complement System Complement system (complements antibody action)
11 plasma proteins that interact to attach to foreign cells
Pore formation
formed by many complement proteins
Destroys integrity of target cell

20. Complement System Enhanced phagocytosis
Attracts phagocytes and makes target cells easier to engulf
= Opsonization
Histamine release
By mast cells and basophils
Increases inflammation and blood flow to region

21. Summary of the Body’s Nonspecific Defenses
Physical Barriers
Prevent approach of
and deny access to
pathogens
Secretions
Epithelium
Duct of eccrine
sweat gland
Hair
Phagocytes
Remove debris
and pathogens
Free
macrophage
Fixed
macrophage
Neutrophil
Eosinophil
Monocyte
Immunological Surveillance
Destroys
abnormal cells
Figure Interferons and the complement system are distributed widely in body fluids
Lysed
abnormal
cell
Natural killer cell
Interferons
Increase resistance of
cells to viral infection;
slow the spread of
disease
Interferons released by activated
lymphocytes, macrophages, or
virus-infected cells 21

22. Summary of the Body’s Nonspecific Defenses
Complement System
Attacks and breaks down the
surfaces of cells, bacteria, and
viruses; attracts phagocytes;
stimulates inflammation
Lysed
pathogen
Complement
Inflammatory Response
• Blood flow increased
• Phagocytes activated
• Damaged area isolated by clotting reaction
• Capillary permeability increased
• Complement activated
• Regional temperature increased
• Specific defenses activated
Multiple effects
Mast cell
Figure Interferons and the complement system are distributed widely in body fluids
Fever
Mobilizes defenses;
accelerates repairs;
inhibits pathogens
Body temperature rises above 37.2°C in
response to pyrogens 22

23. Immunity Power to overcome a specific disease agent Innate immunity
Inherited in genes
Adaptive immunity
Develops after birth
Acquired naturally or artificially
Active or passive

24. Types of
immunity

25. Innate Immunity Differences in physical constitution Species immunity
Individual immunity

26. Adaptive Immunity Develops in a person During lifetime
From encounters with specific harmful agents

27. Antigens Foreign substances that Enter body
Induce immune response of certain lymphocytes
T cells
B cells

28. T Cells Originate in stem cells in bone marrow
Change to T cells in thymus
Become sensitized to specific antigens
Produce cell-mediated immunity
Cytoxic T cells
Helper T cells
Regulatory T cells
Memory T cells
Macrophages

29. Activation of a helper T cell by a macrophage (antigen- presenting cell). 
Zooming In: What is contained in the lysosome that joins the phagocytic vesicle?

30. B Cells and Antibodies
Antibody (Ab) also known as immunoglobulin (Ig) is substance produced in response to antigen
Manufactured by B cells (B lymphocytes)
Must mature in fetal liver or in lymphoid tissue
Provides humoral immunity
Contained in gamma globulin fraction of blood plasma

31. Activation of B cells. The B cell combines with a specific antigen
Activation of B cells. The B cell combines with a specific antigen. The cell divides to form plasma cells, which produce antibodies. Some of the cells develop into memory cells, which protect against reinfection.  
Zooming In: What two types of cells develop from activated B cells?

32. The Antigen–Antibody Reaction
Complement is the enzymatic activity of a group of nonspecific proteins in blood that:
Coats foreign cells
Destroys cells
Promotes inflammation
Attracts phagocytes

33. Naturally Adaptive Immunity
Immunity acquired through contact with a specific
disease organism
Active immunity
Passive immunity

34. Artificially Adaptive Immunity
Vaccination (immunization) can cause a person’s
immune system to manufacture antibodies
Preventive measure
Risk of side effects

35. Types of Vaccines Live Attenuated Toxoid Killed by heat or chemicals
Antigenic component
Genetically engineered

36. Boosters Active immunity does not always last a lifetime
Repeated inoculations (booster shots) help maintain high titer of antibodies in the blood
Number and timing varies with vaccines

37. Examples of Vaccines Whooping cough (pertussis)
Diphtheria, tetanus toxoid (Td)
Haemophilus influenzae type B (Hib)
Pneumococcal vaccine (PCV)
Viral
Inactivated polio, oral polio
Measles (rubeola), mumps, rubella (MMR)
Hepatitis B
Hepatitis A
Chicken pox (varicella); vaccine for shingles now available for those >60 yr
Influenza
Rabies
Rotavirus
HPV (human papillomavirus) for girls 11-26

38. Passive Immunity
Acquired by administration of immune serum (antiserum)
Short-lived immunity
Used in emergencies
Often derived from animals
May cause sensitivity reaction

39. Disorders of the Immune System
Resulting from overactivity
Allergy
Autoimmune disease
Resulting from underactivity
Hereditary
Infections
Environmental

40. Allergy Abnormal reactivity to one’s own tissues Factors Disease
Loss of immune system control
Cross-reaction of antibodies and self antigens
Treatments
Immune-suppressing drugs
Chemotherapy/stem cell replacement

41. Immune Deficiency Diseases
Failure of immune system
May involve any part of system
Varies in severity
Congenital or acquired (e.g., AIDS)
HIV
A retrovirus; uses reverse transcriptase enzyme

42. Multiple Myeloma Cancer of blood-forming bone marrow cells
Effects of disease
Lowered resistance to infection
Anemia
Bone pain
Bone tissue loss
Kidney failure
Treatment
Chemotherapy
Bone marrow transplants

43. The Immune System and Cancer
Immune surveillance
Declines with age
Immunotherapy
T cells activated with interleukin
Vaccines

44. Transplantation and Rejection Syndrome
Caused by normal antigen–antibody reaction
Reduced by
Tissue typing
Immune suppression drugs

45. End of Presentation