Germs and Vaccines

Recent BWH research about germs and how our body fights them can help us build better vaccines.

Science is ever-evolving. What we know about germs and how our body fights them is no exception – and it’s leading BWH researchers to build better vaccines.

In high school biology, I recall watching an animation of immune cells fighting off germs. In the animation, a virus – pictured as a gooey ball covered in spiky nodules – enters the blood stream, a fluid mixture of red blood cells, white blood cells, and platelets. The white blood cells (our immune cells, including both T- and B-cells) suddenly spring into action, identify the invading force, and attack it. The germ (and any offspring it introduced to the system) is killed. But the immune cells file that germ type in their memory and, like soldiers on guard, stand ever-ready to attack – this time stronger and faster – should that germ type ever try to invade again.

According to the latest research from Brigham and Women’s Hospital, that old animation isn’t entirely wrong. But it’s not the whole story either.

It’s true that germs – which can take the form of viruses, bacteria, or fungi and can invade our body through our skin, GI tract, lungs, or oral or reproductive linings – set disease in motion. And although my high school animation wasn’t clear on this part, scientists have long known that our T-cells don’t just wait in the blood stream. If a germ enters through the skin, for instance, the T-cells rush there, enter the tissues, and kill the virus.

But here’s what’s new: Scientists had assumed that the T-cells, their mission accomplished, then returned to the bloodstream. It turns out that isn’t the case. A team of BWH researchers – led by Dr. Thomas Kupper, chairman of the BWH Department of Dermatology, and Dr. Rachael Clark, dermatologist – recently discovered that some of these immune cells remain in the tissue, often for months to years, waiting for the virus to return.

The BWH research team has named these cells that stayed behind in the skin “tissue resident memory T-cells,” and those that returned to the bloodstream “central memory T-cells.” Tissue resident memory T-cells have been found in the skin, lung, mouth, and intestines.

This is big news, in large part because it changes the way we can think about vaccines. Current vaccines help the body make antibodies, a type of germ-fighting protein made by immune cells called B-cells. But Dr. Kupper believes that the key to immunization is to make vaccines that help the body make tissue resident memory T-cells. These T-cells that live in tissues “really represent our first line of defense,” says Kupper. “So that as soon as the virus breaches the barrier it can be attacked.”

The National Institutes of Health (NIH), fascinated by the far-reaching potential of this research, awarded Kupper and Clark a $6 million Common Fund’s Transformative Research grant (one of only 17 awarded nationally) to explore how their findings can help in the development of more effective vaccines.

And so it is that vaccines, like all of science, continue to evolve. Future vaccines might not look so different on the outside. But on the inside, they may be fighting a very different type of battle.

– Linda W

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