The role of polysialic acid in T cell immunity

White blood cells or leukocytes - the cells forming our immune system - are extremely migratory. Whenever there is an infection in the body they actively relocate from the blood to different tissues in order to locally fight the pathogen or form memory responses. In order to reach the correct site in the body, leukocytes have to be directionally steered. The steering signals are proteins of the chemokine family signaling molecules that distribute in the extracellular space and attract the migratory leukocytes. In order to provide a directional signal, chemokines form gradients in the tissue and these gradients can be interpreted by the leukocyte. How chemokine gradients are formed in tissues is poorly understood. Chemokines do not distribute freely by diffusion, but interact with glycosylated proteins presented on cells or in the connective tissue. In this proposal we aim to understand, how a specific form of glycosylation namely sialylation affects the distribution and the sensing of chemokines. We aim at studying this process in vitro, where we can directly follow the chemotactic behavior of leukocytes. We will also investigate the effect of sialic acid-chemokine interaction in vivo, including its role in the control of adaptive immunity.