Carena I, Shamshiev A, Donda A, Colonna M, Libero GD. Major histocompatibility complex class I molecules modulate activation threshold and early signaling of T cell antigen receptor-gamma/delta stimulated by nonpeptidic ligands.
J Exp Med 1997;
186:1769-74. [PMID:
9362537 PMCID:
PMC2199143 DOI:
10.1084/jem.186.10.1769]
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Abstract
Killer cell inhibitory receptors and CD94-NKG2-A/B heterodimers are major histocompatibility complex class I-specific inhibitory receptors expressed by natural killer cells, T cell antigen receptor (TCR)-gamma/delta cells, and a subset of TCR-alpha/beta cells. We studied the functional interaction between TCR-gamma/delta and CD94, this inhibitory receptor being expressed on the majority of gamma/delta T cells. When engaged by human histocompatibility leukocyte antigen class I molecules, CD94 downmodulates activation of human TCR-gamma/delta by phosphorylated ligands. CD94-mediated inhibition is more effective at low than at high doses of TCR ligand, which may focus T cell responses towards antigen-presenting cells presenting high amounts of antigen. CD94 engagement has major effects on TCR signaling cascade. It facilitates recruitment of SHP-1 phosphatase to TCR-CD3 complex and affects phosphorylation of Lck and ZAP-70 kinase, but not of CD3 zeta chain upon TCR triggering. These events may cause abortion of proximal TCR-mediated signaling and set a higher TCR activation threshold.
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