White blood cell

Immune cells play surprising role in steady heartbeat

macrophages and heart cells
IT’S ELECTRIFYING Macrophages (green) “plug in” to heart cells (light purple and pink), providing an electrical boost that helps the heart cells contract and pump blood, a study in mice finds.

Immune system cells may help your heart keep the beat. These cells, called macrophages, usually protect the body from invading pathogens. But a new study published April 20 in Cell shows that in mice, the immune cells help electricity flow between muscle cells to keep the organ pumping.

Macrophages squeeze in between heart muscle cells, called cardiomyocytes. These muscle cells rhythmically contract in response to electrical signals, pumping blood through the heart. By “plugging in” to the cardiomyocytes, macrophages help the heart cells receive the signals and stay on beat.

Researchers have known for a couple of years that macrophages live in healthy heart tissue. But their specific functions “were still very much a mystery,” says Edward Thorp, an immunologist at Northwestern University’s Feinberg School of Medicine in Chicago. He calls the study’s conclusion that macrophages electrically couple with cardiomyocytes “paradigm shifting.” It highlights “the functional diversity and physiologic importance of macrophages, beyond their role in host defense,” Thorp says.

Matthias Nahrendorf, a cell biologist at Harvard Medical School, stumbled onto this electrifying find by accident.

Curious about how macrophages impact the heart, he tried to perform a cardiac MRI on a mouse genetically engineered to not have the immune cells. But the rodent’s heartbeat was too slow and irregular to…

Engineered immune cells boost leukemia survival for some

CAR-T cell attacking a leukemia cell
IMMUNE ATTACK Doctors can engineer a patient’s own immune cells to kill cancer cells. These engineered cells, called CAR-T cells, were effective for some people against relapses of leukemia over the long term. Here, a CAR-T cell (red) attacks a leukemia cell (yellow).

WASHINGTON — Immune cells engineered to hunt and destroy cancer cells may help some people with acute lymphoblastic leukemia (ALL) live much longer.

Outcomes depended upon disease severity before treatment, oncologist Jae Park reported April 3 at the American Association for Cancer Research annual meeting.

In ALL — expected to strike 5,970 people and kill 1,440 in the United States in 2017 — immune cells called B cells grow out of control in bone marrow and can spread to other tissues. Overall, five-year survival rates are 71 percent. But fewer than 10…