The cover shows a histological analysis of an ear section from a C57BL/6 mouse that was first sensitised with 2,4-dinitrofluorobenzene on the belly and then challenged 4 days later with 2,4-dinitrofluorobenzene on the ear. Haematoxylin and eosin staining shows massive skin infiltration by mononuclear cells and granulocytes 24 h after challenge. The image is from Rouzaire et al. (pp. 80–88) in which the authors show that NK cells and T cells induce different types of inflammatory reactions in the skin during recall responses to haptens; of note, NK cell-mediated pathogenesis does not rely on cellular infiltrate.