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Eur J Immunol. 1994 Feb;24(2):348-54.

T cell long-term hyporesponsiveness follows antigen receptor engagement and results from defective signal transduction.

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Laboratoire de Physiologie Animale, Universite Libre de Bruxelles, Belgium.


T cell receptor (TCR)-mediated stimulation of T hybridomas leads to cell activation and lymphokine production that is followed by a long-term hyporesponsiveness. To investigate the biochemical events involved in the induction and maintenance of this antigen receptor hyporesponsiveness or anergy, we have expressed a G protein/PLC beta 1-coupled muscarinic subtype 1 acetylcholine receptor in a murine T cell hybrid. Transfected cells were capable of responding to both muscarinic agonists and TCR ligands by inducing interleukin-2 secretion that was sensitive to cyclosporin A and dexamethasone. Both receptors induced tyrosine kinase (TK) activity, but muscarinic stimulation did not affect tyrosine phosphorylation of PLC gamma 1, nor did the TK inhibitor, herbimycin, block muscarinic receptor-mediated calcium mobilization. These data indicate that in T cells, the muscarinic receptor mediates T cell effector functions by regulating a TK-independent proximal pathway which later converges with the TCR pathway. Using these cells, we have explored the long-term consequences of T cell stimulation via antigen or muscarinic receptors. Our results show that hyporesponsiveness specifically follows TCR engagement and appears to result from a defect in the early signal transduction initiated by TCR cross-linking. A study of TCR-mediated signaling supports this model by showing that tyrosine phosphorylation and calcium mobilization are deficient in hyporesponsive T cells.

[Indexed for MEDLINE]

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