Download Natural (Innate) Immunity

Student's Guide
Historical background
 1798, Jenner Cowpox vaccines, induced
immunity against smallpox
 1885, Louis Pasteur Vaccine against rabies
• Other used Inactivated diphtheria toxins as a
vaccine against diphtheria (the protective
effect were found to be in the serum)
• Serum factor called Antibody
 1883, Metchnikoff certain white blood cells
are able to ingest and destroy micro-organisms
and other foreign material (Phagocytes)
 The process was called Phagocytosis
 So by 1890, it was understood that the immune
system is composed of:
Cells & Molecules
 We can summarize the activities of the immune system as follows:
A. Immunity itself is either natural or adaptive
B. The immune response is either humoral or cellular
Natural (Innate) Immunity
o
o
o
o
Non-specific, does not depend on memory
Act as the first line of defense
Rapid in action but short-lived
It has other barriers (anatomical, physiological) eg skin, mucous , temperature,
chemicals pH, lysozyme, complement, acute phase proteins, interferons
Adaptive (Acquired) Immunity
 Depends on lymphocytes
 Specific, since lymphocytes have specific receptors
 Have memory (measles and mumps).
Innate & acquired immunity do not work separately. They always cooperate
Both the innate and adaptive immune system have cellular and humoral
immunity components (see table)
Components of the innate and adaptive immune systems
Natural
Cells
Molecules
Speed & duration
Adaptive
• Phagocytes
– Neutrophils
– Macrophage
– Eosinophil
• Mast cells, basophils
• Natural killer cells
• Lymphocytes
– B cells
– T cells
• Helper
• cytotoxic
• Complement
• Cytokines (e.g interferon)
• Acute phase proteins
• Antibodies
• Cytokines (e.g interleukins)
• Rapid, short lived
• Slow, prolonged, can increase with exposure
Development of memory • No
• Yes
Innate defenses can be divided into
1. Barriers to infections
 Physical & mechanical:
Skin & mucosal membranes act as physical barriers preventing
entry of pathogens
Flushing action by tears, saliva & urine protects epithelial
surfaces against colonization
High oxygen tension in the lungs and body temperature can
inhibit microbial growth
In the respiratory tract, mucus lining can trap microorganisms.
The trapped pathogens can then be expelled by
i.Beating cilia
ii.Coughing
iii.Sneezing
 Chemical:
i. The growth of microorganisms is inhibited at acidic pH (eg. stomach &
vagina)
ii. Lactic acid and fatty acids in sebum (sebaceous gland secretion) maintain
skin pH between 3-5
iii.Enzymes (lysozymes) found in the saliva, sweat and tears can destroy
microorganisms.
 Biological:
Normal bacterial flora (non pathogenic) can colonize epithelia surfaces and
protect by Competition with pathogenic bacteria for nutrients & attachment
sites
2. Plasma proteins: e.g complement, acute phase proteins,
cytokines (mediate destruction of microorganisms).
3. Cellular
components
eg.
Polymorphonuclear
neutrophils (PMNs) + other leukocytes + macrophages
that are able to phagocytose infected cells
Text Books
Immunology an illustrated outline:
David Male
Molecular and cellular immunology:
Abbas