T-cell receptors and coreceptor molecules are both large proteins displayed on the surface of T cells, and they play an essential role during the beginning of an immune response. T cells become activated after their T-cell receptor recognizes antigen -- small pieces of foreign pathogens -- on the surface of other cells. Coreceptors, while they do not recognize foreign antigen, also bind to molecules on neighboring cells and help in T cell activation.
Although the basic events and consequences of T cell activation have been understood for years, immunologists have long debated some of the specific details. One of the major points of contention has been over the nature of the interaction between the T cell receptor and coreceptor molecules. They both interact with the same target, but their interaction with each other has been hotly debated.
Some immunologists have suggested that T-cell receptors and coreceptors must come together before the T-cell receptor can sense antigen. Others have suggested that it is the sensing of antigen that brings them together. Now, in an article in the August issue of the journal Nature Immunology, Scripps Research Professor Nicholas Gascoigne, Ph.D., research associate Pia Yachi, a graduate of the institute's Kellogg School of Science and Technology, and their colleagues show that it is the latter -- T-cell receptors and CD8 coreceptors are brought together during antigen sensing.
"They are actually pulled together during antigen recognition and are not close together before," says Gascoigne, who observed this with the technique of fluorescence resonance energy transfer (FRET), a sophisticated way of looking at the real-time interactions between molecules in living cells.
Contact: Jason Bardi
Scripps Research Institute