Designing an improved T-cell mobilising CXCL10 mutant through enhanced GAG binding affinity.

The chemokine CXCL10 is released by a plethora of cells, including immune and metastatic cancer cells, following stimulation with interferon-gamma. It acts via its GPC receptor on T-cells attracting them to various target tissues. Glycosaminoglycans (GAGs) are regarded as co-receptors of chemokines, which enable the establishment of a chemotactic gradient for target cell migration. We have engineered human CXCL10 towards improved T-cell mobilisation by implementing a single site-directed mutation N20K into the protein, which leads to a higher GAG binding affinity compared to the wild type. Interestingly, this mutation not only increased T-cell migration in a transendothelial migration assay, the mutant intensified T-cell chemotaxis also in a Boyden chamber set-up thereby indicating a strong role of T-cell-localised GAGs on leukocyte migration. A CXCL10 mutant with increased GAG-binding affinity could therefore potentially serve as a T-cell mobiliser in pathological conditions where the immune surveillance of the target tissue is impaired, as is the case for most solid tumors.