Dual TCR-expressing T lymphocytes in health and disease.

The authors briefly review recent experimental advances in elucidating the role of dual T cell receptor (TCR)-expressing lymphocytes in the development of diseases with special emphasis on autoimmunity. Moreover, they summarize present knowledge about these cells concerning their proportion among peripheral blood mononuclear cells, their functionality, and their impact on allorecognition and memory both in humans and in mice. Finally, they describe disease-associated clonal expansions of dual TCR-expressing cells in humans, most of which have been observed in peripheral T cell malignancies. Other cases occurred in inflammatory bowel disease and in HIV infection. They propose that expression of two distinct TCR on malignant T lymphocytes might be much higher than is suggested by the few cases described so far, and that their presence might impinge on therapeutic immunization strategies which make use of the TCR itself as a target.