A simple and neat presentation on Natural immunity aka innate immunity

1. Dr.Riyaz Sheriff M.D

3. Types of disease
 Pathogenic Organisms
 Genetic Disorders
 Toxic Chemicals
 Other Environmental Factors
 Physical Damage to Organs
 Nutritional Disorders

4. Types of Pathogens
 Bacteria
 Viruses
 Protozoan
 Fungi
 Animal
 Parasites

5. How do these cause disease?
 Utilization of host nutrition.
 Physical damage to host tissues
 Production of toxic substances
 Chromosomal and gene damage
 Body cells behave abnormally

6. So what does the body do??
• Fight against the harmful cause !
• Immunity
• It is the resistance offered by the body towards
microorganisms and their products

7. CELL WALL
PLASMA MEMBRANE
CYTOPLASM
GENETIC MATERIAL
BACTERIA

8. VIRUS
ENVELOPE
CAPSID
GENETIC MATERIAL

9. IMMUNITY
IMMUNITY
INNATE
NON
SPECIFIC
SPECIES
RACE
INDIVIDUAL
SPECIFIC
SPECIES
RACE
INDIVIDUAL
ACQUIRED
ACTIVE
NATURAL
ARTIFICIAL
PASSIVE
NATURAL
ARTIFICIAL

10. INNATE IMMUNITY
INNATE /NATURAL IMMUNITY
NON SPECIFIC
SPECIES RACE INDIVIDUAL
SPECIFIC
SPECIES RACE INDIVIDUAL

11. Innate immunity / natural
immunity
 Genetics
 No relation to prior exposure
 No relation with immunization
 Can be
 General type of innate immunity
 Degree of resistance to infections in general
 Specific type of innate immunity
 Degree of resistance to one particular pathogen

12. LEVELS OF INNATE IMMUNITY
• Species level
– All members of the same species do not respond to
a particular pathogen. Eg: Humans are not affected
by plant pathogens
• Racial immunity
– All members of a particular race are resistant to
certain infections. Eg: people of certain African
tribes do not develop Plasmodium falciparum
malaria

13. LEVELS OF INNATE IMMUNITY
• Individual immunity
– The level of immunity among the individuals.

14. Factors affecting innate
immunity
AGE HORMONES NUTRITION

15. Factors affecting innate
immunity
• AGE
– Extremes of age contract infections fast
– Fetus in utero is protected from maternal infections by
PLACENTA
• Exceptions :RUBELLA, HERPES, CMV & TOXOPLASMA
• May cause deformity or death
– New borns are more susceptible to infections.
• Due to immaturuty of immune system
• Reason for using young ones in animal experiments
– Some infections are more prevalent in younger
children, incidence comes down with onset of puberty
• Tinea capitis infection
• Gonococcal infection

16. Factors affecting innate
immunity
• AGE
• Few diseases present aggressively in adulthood
– Poliomyelitis
– Chicken pox
• Older people develop infections due to waning
immunity

17. Factors affecting innate
immunity
• HORMONES
– Diabetes mellitus
– Hypothyroidism
– Adrenal dysfunction
• Corticosteroids :
– Anti-inflammatory, Antiphagocytic.
– Suppress antibody formation & Hypersensitivity
• Pregnancy : High steroid state
• Stress : Release of steroid hormones

18. Factors affecting innate
immunity
• NUTRITION
• Complex mechanism
• Reduces both cell mediated and humoral
immunity
• Conversely
– Famine struck patients with Malaria do not
develop fever till nutrition improves
– Some viruses do not multiply in severely
malnourished.

19. Mechanisms of innate immunity
 Epithelial surface: Mechanical barrier
 Bactericidal activity
 Sweat : High salt concentration
 Sebaceous secretions
 Long chain fatty acids
 Mucosa: Respiratory tract
 Architecture of nose
 Mucus lining of epithelium
 Swallow/Cough reflex
 Cilia in respiratory tract
 Secretions

20. Mechanisms of innate immunity
 Mouth
 Saliva
 Digestive juice
 Acidity of stomach
 Duonenum to ileum : progressively alkaline
 Intesinal mucosa covered with lacelike network of mucus..
 Conjunctiva
 Flushing action of tears
 Antibacterial : Lysozyme
 Splits polysaccharide components of cell wall
 Genitourinary system
 Flushing action of urine
 Antibacterial : Spermine , Zinc
 Acidity of adult vagina : fermentation of glycogen in epithelial cells by
bacilli

21.  Antibacterial substances in blood & tissues
 Complement system
 ß lysin
 Leukins from Leucocytes
 Plakins from Platelets
 Lactic acid found in muscle, tissue & inflammatory
areas
 Lactoperoxidase in milk
 Interferons for killing viruses
Mechanisms of innate immunity

22. Microbial antagonism
Resident microbial flora prevent colonization
by pathogens
Alteration of normal flora leads to
development of infections
Germ – free animals are extremely susceptible
to infections

23. Cellular factors
• Phagocytosis
• Metchnikoff described phagocytes
PHAGOCYTES
MICROPHAGES
POLYMORPHO
NUCLEAR
LEUCOCYTES
MACROPHAGES
HISTIOCYTES
(WANDERING)
FIXED
RETICULOENDO
HELIAL CELLS
MONOCYTES
(BLOOD)

24. Cellular factors
• Inflammation releases chemotactic substances.
• Chemotactic substances attract phagocytes in
large numbers
• Bacteria phagocytosed into vacuole called
phagosome
• This phagosome fuses with lysosomes 
phagolysosome

25. Cellular factors
• Bacteria destroyed by lytic enzymes
• Exception : some bacteria resist killing and
multiply actively inside the phagosome Eg.,
Brucella , Lepra bacilli
• Natural Killer (NK) cells are specialized subset
of cells for defense against Viral infections and
tumors. NK cells are activated by interferons

26. Inflammation
• Tissue injury, Irritation, entry of Pathogen
• Important, Non specific Defense mechanism
• Vasocontriction followed by vasodilatation
• Slowing of blood flow and margination of
leucocytes
• Chemotactic substances attract more leucocytes
• Leucocytes reach the site via diapedisis
• Phagoytosis
• Out pouring of plasma dilutes toxic products
• Fibrin layer walls off the infected area

27. Fever
• A natural defense mechanism
• Accelerates physiological processes
• Destroys infecting pathogen
• Fever therapy was followed for syphilis before
antibiotic era
• Fever stimulates production of interferon , hence
helping in recovery from viral infections

28. Acute phase proteins
• Infection / Injury leads to increase in plasma
concentration of certain proteins  Acute phase
proteins
• C-reactive protein (CRP)
• Mannose binding protein
• Alpha – 1 – acid glycoprotein
• Serum amyloid P component
• Activate the alternative complement pathway
• Enhance hose resistance
• Prevent tissue injury
• Promote repair of inflammatory lesions