The optimal activation of naive CD4+ T-cells requires two signals: the first from the T-cell receptor complex (TCR/CD3) and the second from co-receptors. In contrast to memory T-cells, co-stimulation of naive CD4+ T-cells depends only on CD28 signalling and to lesser extent on chemokines CCL21 and CXCL12 (SDF-1α), whose primary function is to induce chemotaxis. Despite the crucial importance of co-stimulation for an efficient CD4+ T-cell activation and consequent modulation of adaptive immune responses, the interplay between CD28 and G-protein-coupled multi-spanner chemokine receptor (GPCR) co-stimulation is unclear. Therefore, I am trying to elucidate the role of such dual co-stimulation in the regulation of proliferation, survival, motility and effector functions in CD4+ T-cells.
