b-cell §

B cells are at the centre of the adaptive humoral immune system and are responsible for the production of antigen-specific immunoglobulin.

Development §

Igs consist of two identical heavy and light chains which are joined by disulphide bonds. During the B cell development the Ig heavy chain is rearranged with d-j recombination in the common lymphoid progenitors and pre-pro b cells. Followed by V(D)J recombination, to form the pre-b cell receptor. Quiescent small pre b cells undergo v-j rearrangement of the Ig light chain, allowing the production of a complete functional b cell receptor with unique binding site. This is expressed as IgM on the surface of immature b cells.

B-cells initially express the heavy-chain isotypes δ and μ, which is accomplished by alternative mRNA splicing which leads to the expression of immunoglobulins IgM and IgD. The expression of other isotypes such as γ occurs through DNA rearrangements refereed to as class switching and takes place after a b-cell is activated by antigen in an immune response.