Yale Team Reveals How Immune System Gets Primed for Battle

Published: November 8, 2009

New Haven, Conn. — In a study that sheds light on the inner workings of the immune system, a Yale-led team of researchers has revealed hidden details of how CD4+ T helper cells mobilize the body’s immune system to fight infection. The research appears in the November 9 Advance Online Publication of Nature.com.

T helper cells are needed in order to generate the white blood cells that kill virus-infected cells. But the Yale team showed that, even at their strongest, those white blood cells need assistance to actually enter the infected tissue. The mechanism by which they get that help was previously unknown.

The scientists infected mice with Herpes Simplex Virus 2, which causes genital herpes. They found that CD4+ T helper cells secreted the cell-signaling protein interferon-g (IFN- g), which accelerated the recruitment of killer cells to the site of the infection and allowed them to enter the infected tissue to launch their battle.

According to lead author Akiko Iwasaki, Ph.D, associate professor of immunobiology at Yale School of Medicine, “Our data indicate that the help is actually indirect – the CD4+ T cells alter the local tissue environment, inducing the expression of proteins necessary for killer cells to enter from the bloodstream to the site of infection.”

How CD4+ T cells help killer cells infiltrate infected tissue

Researchers hope that in the future they can use this finding to design more effective treatment of infectious diseases, as well as autoimmune disorders and cancer. Iwasaki said, “Our research could help design new cancer treatment methods that enable killer cells to enter the tumor mass and destroy it. And in autoimmune diseases, it could help researchers prevent the unwanted migration of killer cells that harm healthy organs.”

Other researchers were Yusuke Nakanishi of Yale School of Medicine, and Bao Lu and Craig Gerard of Harvard Medical School.

The research was supported by grants from the National Institutes of Health.

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