We have recently become aware of a situation that necessitates a correction of the publication below. Also find enclosed a supporting statement from Peprotech. All the authors request that you publish the following clarification, along with Peprotech's statement, as rapidly as possible. Mikhail A, Beck EX, Shafer A, Barut B, Smith-Gbur J, Zupancic T, Schweitzer AC, Cioffi JA, Lacaud G, Ouyang B, Keller G, Snodgrass HR: Leptin stimulates fetal and adult erythroid and myeloid development. Blood 89:1507, 1997
We reported that leptin exhibited potent myeloid and erythroid activity on both fetal liver and adult bone marrow cells. Subsequent studies have failed to demonstrate myeloid stimulating activity with recent lots of leptin from Peprotech as well as from other suppliers. All of our results in this publication were ultimately traced back to two lots of leptin (Peprotech murine leptin batch #115761 and #066762-F276). Recent studies indicate that these lots contain a potent myeloid stimulating activity that is not neutralizable with soluble leptin receptor or with a polyclonal anti-leptin antibody. Therefore, the myeloid activity does not appear to be mediated by leptin. This is in contrast to the erythroid stimulating activity that has been consistent across several batches of leptin and fully neutralizable with either soluble leptin receptor or anti-leptin antiserum. We have recently confirmed that these two lots of leptin are contaminated with GM-CSF (lot #115761 has 340 ng/mL and lot #066762-F276 had 178 ng/mL). This conclusion is based on ELISA, Western blots, and neutralization data with anti-murine GM-CSF. Therefore, the conclusion that leptin, by itself, stimulates myeloid differentiation is in error and is retracted. The conclusion that leptin, in combination with Epo, stimulates erythroid differentiation is correct and is not affected by these observations. We apologize for any difficulties that this error has caused.
“PeproTech's internal investigation revealed that there is a possibility that Murine Leptin, Lot #115761 was contaminated by trace amounts of Murine GM-CSF during the vialing and handling process. PeproTech has since updated its vialing and handling protocols to insure that subsequent lots of material are free from trace contamination with other cytokines. The company is offering a replacement of Murine Leptin from a recently produced lot to any researcher who has purchased Lot #115761.”
