A damaged human spinal cord rarely repairs itself. They were once viewed mainly as cells that remove debris, but the researchers found that one subgroup takes on a more active role after spinal cord injury. These cells release a signaling molecule called Il-4, which tells other immune cells to reduce inflammation before it becomes destructive. “They aren’t just there to clear away debris; they act like conductors that tell other immune cells to return to a harmonious rhythm. The results suggest that successful spinal cord regeneration depends not simply on activating or suppressing immunity, but on carefully controlling its timing and intensity.