CCR5 is not the only receptor involved in chemotax

CCR5 is not the only receptor involved in chemotaxis. It almost certainly has to do with preferential use and expression of the various receptors and chemokines by cell type and disease state. For example, in cancer Tregs may preferentially use CCR5 ligands for chemotaxi and NKT may not. There could also be a greater expression of CCR5 on Tregs than NKT. The disease also matters. In cancer there is undoubtedly less of an inflammatory response than in autoimmune diseases. So one would expect less of an overexpression of CCR5 and other receptors.