CLOCK and infection: Interestingly, late day/early night infection led to a stronger recruitment of innate immune cells such as neutrophils and macrophages, which serve as host cells for Leishmania. The rhythms in parasite load, immune cell recruitment and chemokine expression were abolished in mice lacking a circadian clock specifically in cells of hematopoietic origin, demonstrating a role of immune cell clocks in regulating Leishmania infection (Kiessling et al., 2017).