THE ENIGMATIC SPECIFICITY OF GAMMA-DELTA T-CELLS

In most scientific investigations, the study of mechanism follows the study of function. For example, alpha beta T cells were shown to be im portant mediators of immunity before the interaction between the T cel l receptor (TCR) and peptide-MHC complexes was understood. However, so metimes the study of function follows from the study of mechanism. Res earch of gamma delta T cell receptors falls into this category. The ga mma chain of the TCR was first cloned in 1984, which then led to the d iscovery of gamma delta T cells in 1985. Since then, research has focu sed on understanding ligands of the gamma delta TCR with the hope of b etter understanding the function of gamma delta T cells. An initial as sumption was that gamma delta T cells, like alpha beta T cells, recogn ize peptides bound to MHC molecules; however, recent data indicate tha t gamma delta T cells are not biased towards MHC recognition in the sa me way as alpha beta T cells. Although there are intriguing new insigh ts, the specificity and function of gamma delta T cells remains a myst ery.