Theories for planning the formation of antibody
a. Somatic recombination:
- A functional antibody gene is made up in β-lymphocytes by somatically recombining v and c segment into a functional antibody gene combining a few 100 V segments with 20 D segments and 4 J segments generates approx. 10,000 combinations.
- Heavy and light chain combination are included, there are over 10 million unique antibody molecule possible.
Four different types of segments:
- 10 C segments coding for constant region of both chains.
- Several 100 V segments coding for variable portion of protein
- Distinct 4 J segments used for joining V and C segments
- Different 20D segments for diversity of heavy chains
b. Clonal selection theory:
- The β- lymphocytes originate from bone marrow cells.
- Each cell produces antibodies against only specific antigens by the process of somatic recombination.
- As this specific cell type proliferates, it produces a small clone of identical cells, all producing the same antibodies.
- The antibodies remain bound to cell membrane.
- Whenever, they bind to their specific antigen, the cell is stimulated to proliferate rapidly to greatly increase the clone and respond quickly to specific antigen.
- This is clonal selection and also explains how once immunity is developed against a foreign antigen and it remains throughout the lifetime of an individual.
