The neuroendocrine and immune systems are linked through a complex bi-directional network, in which hormones modify immune function, and the immune system, through the action of cytokines, affects neuroendocrine responses involved in the maintenance of body homeostasis. The adipocyte-derived, peptide hormone leptin is a pleiotropic molecule belonging to the helical cytokine family. On pp. 182-187, Matarese et al. suggest the possibility of new leptin-based therapeutic strategies for the treatment of both infection and autoimmune disease.