The researchers then conducted a statistical analysis to estimate the association between elevated concentrations of allergen-specific IgE and total IgE and the risk of developing glioma.

Among women, testing positive for elevated levels of allergen-specific IgE was associated with a 54 percent decreased risk of glioblastoma compared to women who tested negative for allergen-specific IgE. The researchers did not see this association in men.

However, the relation between total IgE levels and glioma risk was not different for men and women, statistically speaking. For men and women combined, testing positive for elevated total IgE was linked to a 25 percent decreased risk of glioma compared with testing negative for total IgE.

The analysis for effects on glioblastoma risk alone suggested a similar decreased risk for both men and women combined whose samples tested positive for high levels of IgE, but the findings were considered borderline in terms of statistical significance, meaning the association could also be attributed to chance.

“There is definitely a difference in the effect of allergen-specific IgE between men and women. And even results for total IgE suggest there still may be a difference between the sexes. The reason for this difference is unknown,” Schwartzbaum said.

What the study does provide evidence for, however, is the likelihood that the immune systems of people with respiratory allergies could have a protective effect against this type of brain cancer. The ability to investigate this association over four decades between blood sampling and tumor diagnosis gave the researchers better insight into the relationship between allergies and tumor risk, Schwartzbaum said.

For example, a positive test for elevated concentrations of total IgE was associated with a 46 percent decreased risk for developing a glioma 20 years later compared to samples testing negative for elevated IgE, according to the analysis. That decreased risk was only about 25 percent in samples that tested positive for high levels of total IgE taken two to 15 years prior to diagnosis.

“There may be a trend - the closer the samples get to the time of diagnosis, the less help the IgE is in decreasing the risk for glioma. However, if the tumor were suppressing allergy, we would expect to see a bigger difference in risk near the time of diagnosis,” Schwartzbaum said.

Schwartzbaum plans to further analyze the serum samples for concentration of cytokines, which are chemical messengers that promote or suppress inflammation as part of the immune response, to see if these proteins have a role in the relationship between elevated IgE levels and lowered tumor risk.

This work was funded by the National Cancer Institute, the National Institutes of Health and a Research Enhancement and Assistance Program grant from Ohio State’s Comprehensive Cancer Center.

Co-authors include Bo Ding, Anders Ahlbom and Maria Feychting of the Karolinska Institutet in Stockholm, Sweden; Tom Borge Johannesen and Tom Grimsrud of the Cancer Registry of Norway; Liv Osnes of Ulleval University Hospital in Oslo, Norway; and Linda Karavodin of Karavodin Preclinical Consulting in Encinitas, Calif.

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Contact: Judith Schwartzbaum, .(JavaScript must be enabled to view this email address) (Dr. Schwartzbaum travels frequently. E-mail is the best way to contact her.)

Written by Emily Caldwell, (614) 292-8310; .(JavaScript must be enabled to view this email address)

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