NEWS 17 April 2026 Study in mice suggests that B cells help regulate muscle performance. B cells, an important component of the immune system, might improve endurance and muscle strength. Credit: Hinterhaus Productions/Getty Immune cells that help to fight off foreign invaders in the body also provide crucial support for muscles during exercise, suggests a mouse study published in Cell today 1 . B cells are the ‘security guards’ of the immune system, identifying harmful pathogens and actively producing antibodies to target them, says Peng Jiang, an immunologist at Tsinghua University in Beijing and anthor of the study. But until now, the cells’ role in metabolism had not been observed. Jiang says this is the first time that a function for these cells that is not associated with the immune system has been described— “a finding completely beyond our initial expectations”, he says.…