1. Innate Immunity: Nonspecific
Defenses of the Host
Chapter 16

2. The Immune Defense System
NONSPECIFIC • SPECIFIC (memory)
• Defends against a • Defends against
variety of microbial specific foreign
attacks invader
• Includes physical, • Includes humoral and
chemical, cellular, cell mediated immune
and inflammatory responses
responses – Humoral- B cells
– Cell-mediated-T cells

6. Nonspecific Immunity
• Physical and chemical barriers:
– Skin and mucous membranes
– Ciliated epithelium
– Lysozyme in tears, sweat
– Saliva
– Peristalsis
– Flow of urine and vaginal secretions

9. Ciliated Epithelium

10. Ciliary Escalator

12. Nonspecific Resistance
• Chemical Factors
– Oil glands
– Low pH
– Sweat glands
– Gastric juices
– Resident flora
• Normal flora
• Transient flora

14. Examples of Normal Flora
Locations
• Eye
• Upper respiratory tract
• Tongue
• Skin
• Teeth
• Stomach
• Small intestine
• Large intestine
• Reproductive system
• Sterile locations: Blood, Cerebral spinal fluid, inside most
organs

19. Secondary Lines of Defense
• Inflammation
• Fever
• Natural Killer Cells
• Phagocytosis
– Chemotaxis
– Adherence
– Ingestion
– Digestion
– Elimination

20. Phagocytosis
• Macrophages- “Big Eaters”
• Neutrophils-actively phagocytic
• Eosinophils-weakly phagocytic

23. Macrophage Eating Bacteria

24. Macrophage Engulfing Dead Cells

25. Inflammation
• Basophils release histamine
• Histamine causes increased vasodilation
and vasopermeability
• Four cardinal signs: redness, swelling,
heat and pain
• Goal is to localize the infection and to heal
the wound

28. Complement
• 20 interacting proteins
• Can be activated by nonspecific or specific
immunity
• End result: increased phagocytosis,
increased inflammation, death of foreign
invader

30. Cytolysis

31. Inflammation Enhanced by
Complement

32. Classical Pathway: AG-AB reaction

33. Alternative Pathway: Initiated by
Pathogen

34. Other nonspecific factors
• Fever- inhibits some microorganisms like
cold viruses
• Natural killer cells-target virus infected
cells and cancer cells
• Interferon-antiviral protein produced in
response to a viral infection