Mechanisms behind Functional Avidity Maturation in T Cells

Figure 1

Simplified model illustrating the differences in T-cell signaling between naïve and primed T cells. In naïve human T cells, TCR engagement leads to activation of p38 through Zap70 resulting in upregulation of VDR and then PLC-γ1 mandatory for the naïve T cells to be activated. For activation, naïve T cells also require CD28 and cytokine receptor signals to induce and stabilize membrane structures and intracellular signaling molecules. In contrast, primed T cells already express PLC-γ1, have a higher DAG and phosphoprotein (P) basal level in specialized membrane structures with a high association of the CD45 molecule. In addition, signaling in primed T cells is rather independent of CD28 costimulatory signals as well as “third-signal” inflammatory cytokines, overall leading to a far more prompt antigenic response.