The document summarizes key aspects of immunology, including: 1) Immunology is the study of the immune system, including its functions of protecting the body from pathogens and eliminating modified or altered self cells. 2) The immune system has both innate and adaptive components. Innate immunity provides non-specific protection while adaptive immunity involves antigen-specific responses with memory. 3) Innate defenses include anatomical barriers and humoral factors like complement and cellular components such as neutrophils and macrophages that recognize and eliminate pathogens through phagocytosis and intracellular killing.

1. IMMUNOLGY
Study of all biological, chemical,
and physical event surrounding
the function of the immune
system.

2. Function of the Immune System
(Self/Non-self Discrimination)
• Operates as a surveillance system
• To protect from pathogens
• Intracellular (e.g. viruses and some
bacteria and parasites)
• Extracellular (e.g. most bacteria, fungi
and parasites)
• To eliminate modified or altered self

3. IMMUNITY

4. Immune System
Immune System
Innate
(Nonspecific)
Adaptive
(Specific)
Cellular Components Humoral Components Cellular immunity Humoral immunity

5. Innate Immunity Specific Immunity
Comparison of Innate and Adaptive
Immunity
• No memory
• No time lag
• Not antigen specific
• A lag period
• Antigen specific
• Development
of memory

6. Innate Host Defenses Against Infection
FIRST LINE OF DEFENCE
• Anatomical barriers–
 Mechanical factors
– Chemical factors
– Biological factors
SECOND LINE OF DEFENCE
• Humoral components–
– Complement
– Coagulation system
– Cytokines
• Cellular components
– Neutrophils
– Monocytes and macrophages
– NK cells
– Eosinophils

7. Non-Specific Defense Mechanism in Humans

8. Anatomical Barriers - Biological Factors
System or Organ Component Mechanism
Skin and mucous
membranes
Normal flora Antimicrobial
substances
Competition for
nutrients
Colonization

9. Anatomical Barriers - Mechanical Factors
System or Organ Cell type Mechanism
Skin Squamous epithelium Physical barrier
Desquamation
Mucous Membranes Non-ciliated epithelium
(e.g. GI tract)
Peristalsis
Ciliated epithelium (e.g.
respiratory tract)
Mucociliary elevator
Epithelium (e.g.
nasopharynx)
Flushing action of
tears, saliva,
mucus, urine

10. Anatomical Barriers - Chemical Factors
System or Organ Component Mechanism
Skin Sweat Anti-microbial fatty
acids
Mucous Membranes HCl (parietal cells)
Tears and saliva
Low pH
Lysozyme and
phospholipase A
Defensins (respiratory & GI
tract)
Antimicrobial
Sufactants (lung) Opsonin

11. Humoral Components
Component Mechanism
Complement Lysis of bacteria and some viruses
Opsonin
Increase in vascular permeability
Recruitment and activation of phagocytic cells
Coagulation system Increase vascular permeability
Recruitment of phagocytic cells
Β-lysin from platelets – a cationic detergent
Lactoferrin and
transferrin
Compete with bacteria for iron
Lysozyme Breaks down bacterial cell walls
Cytokines Various effects

12. Cellular Components
Cell Functions
Neutrophils Phagocytosis and intracellular killing
Inflammation and tissue damage
Macrophages Phagocytosis and intracellular killing
Extracellular killing of infected or altered self
targets
Tissue repair
Antigen presentation for specific immune
response
NK and LAK cells Killing of virus-infected and altered self targets
Eosinophils Killing of certain parasites

13. PHAGOCYTOSIS
AND
INTRACELLULAR
KILLING

14. CELLULAR MECHANISM
1) PHAGOCYTIC CELLS
• Neutrophilic polymorphonuclear leucocytes
• Monocytic macrophages( phagocytosis)
2 ) NATURAL KILLER CELLS
• Non phagocytic lymphoid cells
• Lack surface markers
• Damage virus laden tissue cells
• Immunological surveillance against neoplasia

15. • Characteristic nucleus,
cytoplasm
• Granules
• CD 66 membrane
marker
Phagocytes - Neutrophils (PNMs)

16. Primary granules
contain cationic proteins,
lysozyme, defensins,
elastase and
myeloperoxidase
Secondary granules
contain lysozyme, NADPH
oxidase components,
lactoferrin and B12-binding
protein
azurophilic;
characteristic of young
neutrophils;
specific for mature neutrophils
Characteristics of Neutrophil
Granules

17. • Characteristic nucleus
• Lysosomes
• CD14 membrane marker
Phagocytes - Macrophages

18. PHAGOCYTOSIS
• CHEMOTACTIC FACTORS
• CONTACT AND INGESTION
(PHAGOSOME FORMATION)
• FORMATION OF PHAGOLYSOSOME
• KILLING, DIGESTION OF MICROBES
• RELEASE OF DEBRIS

21. Attachment via Receptors:
IgG Fc R
Scavenger R
Complement R
Toll-like R
Initiation of Phagocytosis

22. Phagocytosis
• Attachment
•Pseudopod extension
•Phagosome formation
•Granule fusion
•Phagolysosome formation

24. Intracellular Killing Pathways
Intracellular Killing
Oxygen
Dependent
Oxygen
Independent
Myleoperoxidase
Dependent
Myleoperoxidase
Independent

25. Effector Molecule Function
Oxygen-Independent Killing in
the Phagolysosome
Cationic proteins (cathepsin) Damage to microbial
membranes
Lysozyme Hydrolyses mucopeptides
in the cell wall
Lactoferrin Deprives pathogens of iron
Hydrolytic enzymes (proteases) Digests killed organisms

26. NON-SPECIFIC KILLER
CELLS
NK and LAK cells
ADCC (K) cell
Activated macrophages
Eosinophils
They all kill foreign
and altered self
targets

27. Natural Killer (NK) cells
also known as large granular
lymphocytes (LGL)
kill virus-infected or
malignant cells
identified by the presence of
CD56 & CD16 and absence
of CD3
activated by IL2 and IFN-γ to
become LAK cells

28. Lymphokine Activated Killer (LAK)
cell
IL2
IFN
IFN
IL2
kills
malignant
cells
kills
transformed
and malignant
cells

29. KILLER -K Cells--- ADCC
morphologically undefined
mediate ADCC
have Fc receptor
recognize antibody coated
targets
could be NK cells (IgG),
macrophages (IgG),
eosinophils (IgE) or other cells
(IgG)

30. Opsonization by IgG Ab by phagocyte

32. INTERFERON
• Small proteins produced by certain WBC and tissues.
• Three major types: alpha– lymphocytes, macrophages
• beta--- fibroblasts
• gamma—T cells
• USED against viral infections and cancer.
MECHANISM IN VIRUS INFECTED CELL:
• Transcription and translation of IFN gene in infected cell
• IFN diffuses out of infected cells
• Attachment --- specific receptors of un infected cells– enters the
nucleus
• IFN activates genes– synthesis of anti-viral proteins --- BLOCK
viral replication ---
ANTI-VIRAL STATE
• IFN does not prevent virus from entering cells but block viral
replication

33. ACTION OF INTERFERONACTION OF INTERFERON

34. Mechanism of alpha and beta Interferon

35. Ant-viral activity of Interferon

36. Effects of IFN gamma

38. ACQURIED SPECIFIC IMMUNITY
• HUMORAL: immune response– B cells stimulated– plasma cells–
Ab (Ig)– destruction extracellular pathogens
• CELLULAR: immune response– T cells sensitized +
macrophages– destruction intracellular pathogens, tumor cells
HUMORAL & CELLULAR CAN BE:
• ACTIVE: Foreign antigens– activate cells of immune system–
Recognition, specificity, destruction, memory
NATURAL- INFECTION
ARTIFICIAL- VACCINATION, IMMUNIZATION
• PASSIVE: preformed antibodies introduced– non immune
person--- protection
NATURAL– TRANSPLACENTAL, BREAST MILK
ARTIFICIAL– GEMMAGLOBULIN, ANTI TOXINS
•