Distinctive calcineurin-dependent (FK506-sensitive) mechanisms regulate the production of the CC chemokines macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and RANTES vs IL-2 and TNF-alpha by activated human T cells.

Calcineurin (CaN) controls the production of multiple cytokines, including IL-2 and TNF-alpha, during T cell activation. However, its role in chemokine production is unclear. Here, we used the CaN inhibitor FK506 to probe for the contribution of CaN in MIP-1alpha, MIP-1beta, and RANTES production at the protein and mRNA levels in human T cells stimulated via CD3/PMA or CD3/CD28. With both modes of activation, FK506 inhibited RANTES production only partially and late during a 3-day culture, whereas it suppressed both MIP-1alpha and MIP-1beta production throughout the culture. However, FK506 inhibition was more pronounced on MIP-1beta than MIP-1alpha, especially in CD3/CD28-activated T cells. Surprisingly, FK506 also significantly reduced MIP-1beta induction by PMA alone. Furthermore, comparison with IL-2 and TNF-alpha revealed that both were more potently inhibited by the drug upon CD3/PMA or CD3/CD28 induction than either MIP-1alpha or MIP-1beta. These differences in FK506 sensitivity were also observed in CD4(+) and CD8(+) T cell subsets. Therefore, all three chemokines are affected by FK506 distinctly from one another and from IL-2 and TNF-alpha, suggesting that CaN participates to different extents in the induction of these cytokines during T cell activation. Further evidence that this induction relies on distinctive mechanisms, depending on the cytokine, came from analyses of the kinetics and cycloheximide sensitivity of cytokine mRNA expression.