CCR6 and myeloid sarcoma: Notably, CCR6+ CD25- CD4+ pro-inflammatory lymphocytes are present in the CSF of MS patients starting from the earliest disease episode, supporting the pivotal involvement of the evolutionarily conserved CCL20-CCR6 axis in the establishment of a pathological loop amplifying local CNS immune responses (Reboldi et al., 2009; Kara et al., 2015).