Transcript Document

Antigens. Antigen structure of
the microorganisms. Immune
cells and their markers
Antigen
Antigen may be any non-self foreign
substance to which lymphocytes respond
 Any antigen consists of:
1. Epitope
2. Non-specific remaining portion
Classification:
1. Complete antigens
2. Haptens (complex and simple)
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Properties of the antigens
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Foreignness
Antigenicity
Specificity
High molecular weight
Solubility or colloidal properties
Antigen specificity.
1.
Heterogenic specificity
2.
Species specificity.
3.
Isospesificity.
4.
Autospecificity
Antigen structure of the
bacterial cell
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O-Ag
K-Ag
H-Ag
Vi-Ag
Other bacterial antigens:
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Protective antigens
Bacterial exotoxins and enzymes
Specificity of bacterial antigens
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Genus antigens
Species antigens
Group specific antigens.
Type specific antigens.
Structure of the immune
system
Lymphoid system consist of the:
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Lymphoid cells (T and B cells)
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Lymphoid organs:
1. Central (primary) organs: thymus and bone marrow
2. Peripheral (secondary) lymphoid organs are:
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T-cells may be subdivided into some
subsets (or subpopulation) due to their
functions:
1.
T- helper (TH)
T- suppressor (TS)
T- regulator (TR)
T- cytotoxic (TC);
Delayed-type hypersensitivity T cells (TDTH);
2.
3.
4.
5.
B-cells
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Activated B-cells can differentiate into
plasma or memory cells
Cytokines
1.
2.
3.
Monokines
Lymphokines
Interleukins (IL)
Types of immune response
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Cellular immune response
Humoral immune response
Immunological memory
Immunological tolerance
Hypersensitivity reactions
Immune response to an antigen
may be of two broad types:
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The humoral or antibody mediated immunity (AMI).
It is mediated by antibodies produced by plasma cell
The cellular or mediated immunity (CMI).
It is mediated by sensitized T-cells
Cellular cooperation in the
immune response
1.
2.
3.
Antigen processing cells (APC) (macrophages
or dendritic cells)
TH cell (either Th1 or Th2)
Either B-cell in the humoral immune response
or TC (TK) cell in the cellular immune response