Analysis of TCR activation kinetics in primary human T cells upon focal or soluble stimulation.

Signaling through the TCR is crucial for the generation of different cellular responses including proliferation, differentiation, and apoptosis. A growing body of evidence indicates that differences in the magnitude and the duration of the signal are critical determinants in eliciting cellular responses. Here, we have analyzed signaling dynamics induced upon TCR ligation in primary human T cells. We used CD3 antibodies either cross-linked in solution (sAbs) or immobilized on microbeads (iAbs), two widely employed methods to stimulate T cells in vitro. We show that classical sAbs stimulation induces a transient and abortive response, whereas iAbs induce sustained TCR-mediated signaling, resulting in productive T-cell responses previously observed only in antigen-specific murine systems. In summary, our analysis documents TCR signaling kinetics and suggests that iAbs are better suited for studying TCR-mediated signaling as they mimic antigen specific systems.