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Nat Immunol. 2002 Mar;3(3):259-64. Epub 2002 Feb 4.

Regulation of Lck activity by CD4 and CD28 in the immunological synapse.

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Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid, Campus Box 8118, St. Louis, MO 63110, USA.


Although the Src family tyrosine kinase Lck is essential for T cell receptor (TCR) signaling, whether or how Lck is activated is unknown. Using a phosphospecific antiserum to Lck, we show here that Lck becomes autophosphorylated when T cells are stimulated by antigen-presenting cells (APCs). We found that TCR cross-linking alone could not stimulate Lck autophosphorylation and CD45 was not required for this process. Instead, the T cell accessory molecules CD4 and CD28 cooperated to induce autophosphorylation of Lck. CD4 recruited Lck to the T cell--APC interface, whereas CD28 sustained Lck activation. These data show how the multiple interactions afforded by the immunological synapse drive efficient and highly specific signaling.

[Indexed for MEDLINE]

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