title: A role for leptin in sustaining lymphopoiesis and myelopoiesis.
abstract: Although leptin is known for its regulation of food intake, it has many emerging roles in immune function. To better define the role of leptin in hematopoietic processes, a leptin-deficient obese mouse (ob/ob) and C57BL/6 lean wild-type controls were compared. Despite their large size and consumption of substantial amounts of nutrients, the ob/ob mice had only 60% as many nucleated cells in their marrow as controls. The greatest impact of leptin deficiency was on the B cell compartment that had 70% fewer cells, reducing the absolute number of pre-B and immature B cells to 21% and 12% of normal, respectively, and indicating a significant reduction in lymphopoiesis in ob/ob mice. Whereas the proportion of myeloids remained nearly normal in the obese mice, they also exhibited a reduction of 40% and 25%, respectively, in absolute numbers of granulocytes and monocytes. Seven days of provision of recombinant leptin promoted substantial lymphopoiesis, increasing the numbers of B cells in the marrow of the obese mice twofold, while doubling and tripling, respectively, the numbers of pre-B and immature B cells. Twelve days of supplementation brought these subpopulations to near-normal proportions. Leptin treatment also facilitated myelopoiesis such that the marrow of the obese mice contained normal numbers of monocytes and granulocytes after 7 days. Taken together, the data support an important role for leptin in sustaining lymphopoiesis and myelopoiesis.
authors.affiliation: Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824-1319, USA.
authors.forename: Kate
authors.initials: K
authors.lastname: Claycombe
authors.forename: Louis E
authors.initials: LE
authors.lastname: King
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Fraker
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology; D006410:Hematopoiesis / Q000502:physiology*; D020738:Leptin / Q000172:deficiency / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009765:Obesity / Q000503:physiopathology*
chemical_list: D020738:Leptin