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

Amy D Holdorf1, Kyeong-Hee Lee, W Richard Burack

  • 1Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid, Campus Box 8118, St. Louis, MO 63110, USA.

Nature Immunology
|February 6, 2002
PubMed

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.

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