Charles Mackay’s early work established new paradigms for lymphocyte migration, particularly pathways for the migration of naïve and memory T cells. This work has important implications for understanding immune responses, and the structure and rationalisation of the immune system. Charles Mackay also made important contributions in the fields of chemoattractant receptors. He discovered human eotaxin and CCR3, which facilitate eosinophil migration to tissues. He also characterized the expression, function, and role in HIV entry of several chemokine receptors, including CCR5, CXCR4 and CC3. He is an internationally recognised authority on chemoattractant receptors, and their use as targets for anti-inflammatory therapy.