1. Innate and Adaptive Immunity

2. Innate (Natural) Immunity:
Inborn resistance.
present the first time a pathogen is encountered (does not require prior exposure).
Not specific.
not modified by repeated exposure to the pathogen.

3. Adaptive (Acquired) Immunity:
weak or absent at the first exposure.
Specific.
increases dramatically with subsequent exposures to the same pathogen (memory).

4. Components of innate immunity:
Cell mediated immunity.
Humoral (soluble) immunity.
Types of adaptive immunity
Humoral (soluble)immunity.

5. Cells of Innate Immunity:
Phagocytes: - Monocytes and macrophages: blood stream and tissues. - Dendritic cells: lung, skin and GIT mucosa. Granular leukocytes: - Neutrophils, and eosinophils. - Basophils and mast cells. Natural killer cells (NK).

6. Soluble Mediators of Innate Immunity:
Proteins and enzymes.
Cytokines & type 1 interferons.
Complement (C3b: opsonization).

7. Proteins and Enzymes
A variety of proteins and enzymes (present in human blood and tissue fluids) are considered the first part of innate immunity Example: C reactive protein (CRP), lysozymes and defensins.
Proteins and enzymes
Major microbial targets
Effects
Lysozyme and defensins
Bacterial wall and membrane
digestion
CRP
Polysaccharides of microbes
Opsonization
Mannose binding proteins
Mann glycoprotein
and complement activation

8. Cytokines and Type I Interferons:
Cytokines: IL-1, IL-6, IL-12, and TNFα produced by activated phagocytes.
Type I interferons:
INFs are rapidly produced, within minutes by infected cells (virus infection).
INFs activate phagocytosis and apoptosis of infected cells.
IFN- α produced by dendritic cells.
IFN-β Produced by fibroblasts.

9. Cellular and Humoral Adaptive Immunity:
Immune cells: - T lymphocytes - B lymphocytes - N.K cells. Soluble mediators: - Cytokines: IL-2, IL-3, IL-10,IL Interferons: INF-γ (Gamma). - Complement. Soluble and cell-bounded proteins: -The Immunoglobulins.

10. T lymphocyte & B lymphocytes
Complement
Cytokines: IL1, IL6, IL12 & TNFα.
Interferons: IFα and IFβ.
Cytokines: IL2, IL3, IL10 & IL13.
Interferons: IFγ
Immunoglobulins. n
Phagocytes: monocytes, macrophages & DC
Granular leukocytes
T lymphocyte & B lymphocytes
NK cell

11. Antigens, Immunogens , Epitopes and Haptens

12. Antigen: Is a molecule or part of a molecule that is recognized by the immune system. Immunogen: Is an antigen that evokes a specific, positive immune response. Example: Injecting a laboratory animal by human chromosome anti-DNA antibodies and anti-histons antibodies will be produced.

13. Epitopes (The Antigenic determinants):
The smallest part of an antigen or immunogen that can be recognized by the B & T cells receptors. So it is the basic recognition element.
A single antigen molecule may have several different epitopes.
Immunodominant epitope is an epitope that can stimulate a greater antibody response than others. n

14. N
epitopes

15. Immunogenicity and Properties of Immunogen:
Immunogenicity is the ability of immunogen to activate immune response.
Properties of Immunogen:
Foreignness.
Size.
Chemical nature
Complexity.

16. Foreignness:
Immune system can discriminate between foreign and self substance (self & non self).
Size:
Molecular weight of at least 10,000 Dalton (10 kDa).
Chemical nature: Proteins (polypeptide) are good immunogens Carbohydrates, steroids, and lipids are poor immunogens.

17. As the chemical complexity increases; the immunogenicity increases.
Homopolymers are poor immunogens regardless of size, while heteropolymers are strong immunogens.
Proteins are heteropolymers (different amino acids).

18. Which of these antigens is more immunogenic?
epitopes

19. Epitopes Recognition
B cell receptors can recognize epitopes whether they are:
Free soluble molecules.
Surface-bound molecules.
Degraded fragments.
T cell receptors can bind only to epitopes which are surface-bound molecules.

20. Superantigen:
Is a substance such as a bacterial toxin that is capable of stimulating multiple T lymphocytes, leading to release of relatively large quantities of cytokines.
Phagocytosis process is not required for this type of activation.

22. n

23. (Land-Steiner’s experiment).
Hapten:
Small, usually non-biologic molecules that bind to immune cells receptors but cannot by themselves induce a specific immune response.
(Land-Steiner’s experiment).
Injected a mice with:
hapten No immune response
carrier (protein) anti carrier
Hapten + carrier anti-hapten +anti- carrier

24. T-cell Dependent and T-cell Independent Antigens:
Antigens are classified as either T-cell dependent or T-cell independent.
T cell dependent antigen activates immune system depending on T- lymphocytes.

25. T-cell dependent antigen T-cell independent Antigen
Structural properties
Complex
Simple
Chemical nature
Proteins, glycoprotein, and lipoproteins
Polysaccharide; bacterial
Lipopolysaccharide.
Antibody - class induced
IgG, IgM, IgA, IgD, and
IgE
Only IgM
Immunological Memory
yes No
Present in most Pathogens