Signals through T cell receptor-ζ chain alone are insufficient to prime resting T lymphocytes

Abstract

Activation studies performed with transfected T cell hybridomas and tumors revealed that chimeric molecules containing the CD3ε or ζ chain intracytoplasmic portions can induce the complete effector functions normally seen only when the complete T cell receptor (TCR)/CD3 complexes of T lymphocytes are triggered. Therefore, the ζ chain, with its three antigen recognition activation motives, is thought to connect the antigen-binding Ti chains with the intracellular signaling machinery of the T cell. Here we demonstrate that the cytoplasmic portion of the TCR-ζ chain is not sufficient to activate resting T lymphocytes when cells from transgenic mice expressing a chimeric ζ receptor are used. However, after (in vivo and in vitro) activation through their endogenous TCR/CD3 complexes, the preactivated T lymphocytes could be triggered through the ζ chimera to the same extent as when they were activated through their endogenous TCR/CD3 complexes. They were able to proliferate and elicit cytotoxic functions when triggered through their ζ chimeras. These results suggest that the triggering requirements for effector functions seem to be different in resting than in activated T cells.