Stanford discovers explosive immune cells in flatworms
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- Stanford researchers identified "ruptoblasts," immune cells in planarian flatworms that burst open, kill nearby cells, and vanish completely within five minutes.
- Postdoctoral researcher Chew Chai discovered the cells while studying fused "Frankenstein" worms that rejected unrelated tissue in a severe, sustained inflammatory response.
- The self-destruction, dubbed "ruptosis," is triggered by the hormone activin and driven by a rapid calcium surge from the cell's endoplasmic reticulum, unfolding in seconds to minutes.
- Ruptoblasts destroyed E. coli bacteria, human kidney cells, and mouse blood cells in lab tests, with damage tightly confined to cells near the blast and no persistent toxicity.
- Unlike T cells and neutrophils, ruptoblasts are glandular cells rather than hematopoietic blood cells produced in bone marrow, according to the study published in Cell.
- Similar cells appeared only in basal bilaterians like flatworms, suggesting vertebrates may have lost this defense because they cannot easily repair tissue damage from the blast.
Why it matters: The discovery gives researchers a concrete, non-hematopoietic model of localized immune killing that is absent from vertebrate biology. Senior author Bo Wang's team explicitly links the mechanism to potential targeted treatments for bacterial infections and tumors, positioning flatworms as an untapped source of immune strategies.
