Recognition of Antigen
What is antigen?
Each toxin or organism contain chemical compound its makeup.
Can initiate acquired immunity.
Most of them are large polysaccharides.
With higher molecular weight - >8000
Has stereochemical character – epitopes – regularly occurring molecular group.
Heptens
Heptens – Molecular weight is low.
Heptens combined with protein and initiate response.
Lymphocyte clones
When antigen contact with lymphocyte only certain lymphocyte activate.
Activated B and T lymphocytes are highly specific for targeted antigen.
Lymphocyte that can produce one B and T specific cells – clone of lymphocytes
Millions of different lymphocytes store in bone marrow capable of producing highly specific B lymphocyte and T lymphocytes.
Origin of Clones
‘Gene segments’ are responsible to produce specific B cells (antibody) and T-cells quality.
These segment can mixed between genes and produce million – billion possible combination .
These combination will produce different type of B cells (antibody) and T-cells.
Activation of a clone
Each B cell has about 100,000 antibody molecules.
Each react only When high specific antigen contact with them.
Then activate long process of producing highly specific antibody.
In T cell, same happen – has surface receptor proteins.
Macrophage helps…..
Macrophage phagocytes most invading organism – partly digest.
Antigenic products are inside cytosol.
Antigen pass to lymphocyte by cell to cell contact.
In additionally, secrete Interleukin-I - promote growth of specific lymphocyte.
Memory cells
Few lymphoblast form by activating B-lymphocyte clone make different B-lymphocyte – memory cells.
Dormant like original clone.
When there is next expose they activate very quickly and overcome antigen.