Scientists discover a hidden immune signal that helps spinal cords regrow

A surprising immune system signal may help explain why zebrafish can regenerate damaged spinal cords so effectively. Researchers found that certain neutrophils release Il-4, which calms harmful inflammation and allows injured nerve fibers to grow again. Without these cells, healing stalled, but adding Il-4 restored regeneration. Scientists now want to know whether the same mechanism could someday be harnessed to improve spinal cord repair in humans.