[Immunoglobulin D--new insights into its structure and function]

The IgD is unique with regard to its structure, differences between species, genetic organization and behaviour in the immune response. With the successful analysis of the structure a new picture of the function has been emerged. The function of the membrane-bound IgD as a trigger receptor of B cells is qualitatively different from the mIgM. The secreted form could act as an intercellular messenger in the network regulation of the immune response. The mechanisms of the induction and maintenance of the immunological memory and tolerance remain unclear.