Boosting the Staying Power of the Immune System

Researchers at the Johns Hopkins Oncology Center have figured out a way to keep the body’s cancer-fighting immune cells awake and responsive to tumor cells far longer than they normally do.

Scientists have long known that it is possible to activate immune cells to recognize molecules found on tumor cells. Over time, the ability of the immune system to respond to cancer cells diminishes.

In the current research, published in the journal Nature Medicine, the Hopkins team, working with genetically engineered mice, used an antibody to a molecule found on the surface of so-called antigen presenting cells (or APCs) to restore the ability of the immune system to respond.

"We believe APCs are key to teaching specialized immune system cells called T-cells to identify and track down cancer cells. Our strategy seeks to activate the APCs so they are better at ‘priming’ T-cells," says Dr. Hyam Levitsky, associate professor of oncology at Johns Hopkins and senior author.

"One reason that immunotherapy of cancer frequently doesn’t work is that it’s very hard to keep the immune system responsive to tumors as they grow," explained Levitsky.

"Activation of the APC has been the critical missing link," said lead author, Dr. Eduardo Sotomayor, a fellow of the Lymphoma Research Foundation of America.

"Our method of activation, which targets CD-40 proteins on the APC, may now be used to provide a stimulant that enhances cancer vaccines used in treatment and, at the very least, prevent the immune system from becoming tolerant to cancer cells," said Sotomayor.

Sources: Johns Hopkins Medical Center, Nature Medicine