Clonal selection

The clone selection theory (English clonal selection theory ) describes in immunology, the phenomenon that all cells that can produce specific antibodies (B- lymphocyte ), as well as its corresponding cell (T- lymphocyte ), all clones of a common parent cell are.

Through a contact with a specific antigen ( progenitor cells ) is stimulated only one clone for the propagation of the variety of these innate immunological mother cells that can bind the epitope of the antigen by an appropriate receptor. This selective signal to the so-called B -cell proliferation occurs at the molecular level by the fact that a T lymphocyte for the key - lock principle to an MHC protein ( class I or class II ) of macrophages or B lymphocytes binds of the antigen presented by recording and processing. After this bond and the release of interleukin -2 by the T cell antigen-presenting cell that begins at first to share uninhibited (B- lymphocyte or macrophage ). The descendants of these cells originally antigen-binding cell thus represent a clonal population dar. During the division differentiate them into antibody-producing cells ( plasma cells) and memory cells.

In theory, every human being has about 1012 variants of the capable for antigen recognition progenitor cells and can thus theoretically these (and only these ) form number of different antibodies. This innate stocking forms the so-called pre-immune Antikörperrepetoire. The different expression of these variants in different individuals also stated that an epidemic always a statistical percentage of those infected has an efficient immunity against the pathogen, as they have randomly over the corresponding cellular clones.

The multitude of different mother cells far exceeds the number of all existing genes of about 20000-24000 in the human genome. The variations of the antibody of specificity is achieved by so-called somatic mutation and intramolecular recombination, as well different genes for the protein chains of the antibody are combined in new ways and for the variable part, there is a so-called gestückeltes gene, with several hundred gene fragments in different places in the genome chained variable are combined and read with different reading frames ( frame shift ).

The clone selection theory was developed in 1957 by Frank Macfarlane Burnet by fusion of the side-chain theory by Paul Ehrlich and the Jerne theory. It is often colloquially referred to incorrectly as " clonal selection".