Leptin: nourishment for the immune system.

Leptin, a protein produced by adipocytes, exerts several functions, including modulation of the immune response. A report in this issue of the European Journal of Immunology describes for the first time the effect of either leptin receptor deficiency or blockade on murine dendritic cell (DC) maturation, survival and function. The study describes how leptin receptor deficiency/blockade delays DC maturation and promotes apoptosis, shifts the balance between pro- and anti-inflammatory cytokine production, and reduces the ability of DC to stimulate CD4(+) lymphocytes. These exciting novel data add an important piece of evidence to the picture of the role of leptin in immunity and inflammation and generate the possibility that many of the effects of leptin on T lymphocytes might be mediated through DC.