T-Cell Receptors e-bog

The importance of thymus-dependent cells, or T cells, in the generation of a successful immune response was first realized in the early sixties. In the follow- ing two decades, a succession of elegant experiments established the antigen specificity of T cells and their ability to perform both as regulatory and effector cells. T cells were shown to be essential in most immune reactions, playing a crucial role in augmenting the activity of effector T and B cells against 'foreign' antigen, as well as in the suppression of effector activity against self antigens. The means by which T cells differentiate 'foreign' from 'self' antigens is based on their recognition of antigen almost exclusively in the context of self major histocompatibility complex products, unlike B cells, which recognize an- tigen alone. It is this recognition, mediated by the T-cell receptor, that sets into motion the diverse cell-cell interactions, which control the differentiation and regulation of the immune response. Although its importance was well established, the molecular nature of the T-cell receptor remained elusive for two decades. Many hypotheses as to its structure and precise function were put forward, using immunoglobulin as a basis for conjecture, but "e;the Holy Grail of Immunology"e; remained ephemeral until three years ago. In the ensuing years, both immunologists and molecular biologists have contributed to an explosion of data unsurpassed by any previous period in the field.