Download 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)

Properties of the antigens





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




O-Ag
K-Ag
H-Ag
Vi-Ag
Other bacterial antigens:


Protective antigens
Bacterial exotoxins and enzymes
Specificity of bacterial antigens




Genus antigens
Species antigens
Group specific antigens.
Type specific antigens.
Structure of the immune
system
Lymphoid system consist of the:

Lymphoid cells (T and B cells)

Lymphoid organs:
1. Central (primary) organs: thymus and bone marrow
2. Peripheral (secondary) lymphoid organs are:

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

Activated B-cells can differentiate into
plasma or memory cells
Cytokines
1.
2.
3.
Monokines
Lymphokines
Interleukins (IL)
Types of immune response





Cellular immune response
Humoral immune response
Immunological memory
Immunological tolerance
Hypersensitivity reactions
Immune response to an antigen
may be of two broad types:




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