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New Test Detects Rare Leukemia More Quickly

MONDAY Oct. 6, 2008 -- A new technique may help doctors diagnose a rare form of leukemia in a matter of hours instead of weeks, researchers say.

Juvenile myelomonocytic leukemia (JMML) occurs in children; symptoms include fevers, poor growth, and infections.

Early diagnosis of JMML is important, since the only cure is a bone marrow transplant. But JMML is currently diagnosed by monitoring the response of JMML cells to a growth-stimulating factor called GM-CSF, which involves two to three weeks of growing cells in the laboratory.

Now, a new study published in the Oct. 7 issue of Cancer Cell may have found a faster way to diagnose this relatively rare leukemia.

For their study, researchers used a new technique that builds on flow cytometry.

In flow cytometry, fluorescently labeled antibodies are used to classify and sort cells based on the proteins on their outer surface. The new approach goes further by sending antibodies inside the cell to bind to target proteins.

To find a way to diagnose leukemia, the researchers used an antibody that binds only to the activated form of a protein called STAT5 in cell samples of 12 patients with JMML.

Eleven of the 12 JMML cell samples displayed abnormally high levels of STAT5 in response to low doses of GM-CSF. Seven out of the eight normal bone marrow samples, and eight out of eight samples from patients with similar -- but not identical disorders -- did not have increased levels of STAT5 in response to GM-CSF.

"I was surprised how much more we can learn about the inner nature of these cells by 'interrogating' them with different conditions," senior co-author Garry Nolan, immunologist and member of the Donald E. and Delia B. Baxter Laboratory in Genetic Pharmacology at Stanford, said in a university news release. "Time and again, we are finding this to be a powerful amplifier of the fate of a diseased cell and a good way to understand why it responds to certain treatments and not others."

Since the new technique can help track disease progress, the researchers hope that it can be used to monitor the effectiveness of potential drug treatments for JMML and other disorders.

"Identifying populations of cells by their responses to specific stimuli will facilitate our ability to assess the efficacy of specific agents in relevant subsets with increased precision," senior-co-author Mignon Loh, an associate professor of clinical pediatrics at the University of California, San Francisco, said in the release.

"In an era of using increasingly sophisticated targeted agents, we hope that these studies will allow investigators to more fully appreciate the specificities of their therapies," said Loh.

Posted: October 2008


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