"In a healthy individual, memory T cells would be produced during the initial influenza infection," she said. "Those cells help protect the individual from a second infection. The response is different from a vaccine, which produces antibodies against a specific strain. The memory T cells target internal proteins common to all strains of the virus. But if the body can't produce these T cells during a primary infection, then the individual has decreased protection from a second infection if the antibody response is not targeted towards the infecting strain."

The new study, by Karlsson, Beck and Patricia Sheridan, Ph.D., UNC research assistant professor of nutrition, shows strong evidence that obesity restricts memory T cell function.

"This kind of novel research could influence public health by changing our views of what the risks factors of obesity are," Karlsson said. "The risks are potentially much more complicated than we've thought."

The next step in Beck's research on obesity effects on influenza is to examine vaccination. In collaboration with researchers in the UNC School of Medicine, Beck's laboratory is running a large National Institutes of Health-sponsored human clinical trial to test the efficacy of influenza vaccination in obese adults.

jimmunol/