The role of L(u)ck in T cell triggering

T cells use a highly complex signaling apparatus to discriminate between a diverse array of foreign antigens and a myriad of self molecules. The precise mechanism whereby signals are communicated from the antigen-binding T cell receptor to the intracellular signal transduction machinery remains a source of intense debate. This Journal Club article highlights recent research elucidating the role of the Src family kinase Lck in T cell triggering. Resting T cells contain a newly described form of preactivated Lck that is both necessary and sufficient for T cell activation but remains uncoupled from the T cell receptor in the absence of antigen. This research allows a reappraisal of the mechanisms underlying T cell triggering.