Lymphocytes and other cell types communicate with each other via chemotactic cytokines, or chemokines. There are presently nineteen (19) different chemokine receptors that collectively respond to forty-nine (49) different ligands. In some rare cases, a single ligand binds to a single receptor. More often though, multiple ligands bind to a single receptor and vice versa. The reason for this redundancy is not fully understood and it certainly complicates assigning functional specificities within this family. To best address this complexity, we use a collection of receptor-transduced cells. The host cells are selected based on their inability to chemotax to the cognate receptor ligand and the assays support moderate throughput profiling activities.