Cutting Edge: Stromal Cell-Derived Factor-1 Is a Costimulator for CD4+ T Cell Activation

Stromal cell-derived factor (SDF)-1 is a chemoattractant for T cells, precursor B cells, monocytes, and neutrophils. SDF-1alpha was also found to up-regulate expression of early activation markers (CD69, CD25, and CD154) by anti-CD3-activated CD4+ T cells. In addition, SDF-1alpha costimulated proliferation of CD4+ T cells and production of IL-2, IFN-gamma, IL-4, and IL-10. Stimulation with SDF-1alpha alone did not induce activation marker expression, proliferation, or cytokine production by the CD4+ T cells. SDF-1alpha-mediated costimulation was blocked by anti-CXC chemokine receptor-4 mAb. RANTES also increased activation marker expression by anti-CD3-stimulated peripheral CD4+ T cells, but less effectively than SDF-1alpha did, and did not up-regulate IL-2 production and proliferation. These results indicate that SDF-1 and CXC chemokine receptor-4 interactions not only play a role in T cell migration but also provide potent costimulatory signals to Ag-stimulated T cells.