2026-06-02 スタンフォード大学
＜関連情報＞
- https://news.stanford.edu/stories/2026/06/flatworms-ruptoblasts-new-type-immune-cell-research
- https://www.cell.com/cell/abstract/S0092-8674(26)00567-2
破裂芽細胞の爆発的な細胞毒性は、ホルモン監視と免疫防御を結びつける Explosive cytotoxicity of ruptoblasts bridges hormone surveillance and immune defense
Chew Chai ∙ Eliya Sultan ∙ Souradeep R. Sarkar ∙ … ∙ Hawa Racine Thiam ∙ Benyamin Rosental ∙ Bo Wang
Cell Published:June 2, 2026
DOI:https://doi.org/10.1016/j.cell.2026.05.008
Graphical abstract
Highlights
- Ruptoblasts are a cytotoxic glandular cell type likely conserved across bilaterians
- Activin triggers explosive ruptosis via ER calcium amplified through the cytoskeleton
- Ruptoblasts drive tissue rejection in planarian chimeras and aid bacterial clearance
- Ruptosis releases potent broad-spectrum cytotoxic agents
Summary
Current understanding of cytotoxic immunity is shaped by hematopoietic-derived cells—T cells, natural killer cells, and neutrophils. Here, we identify “ruptoblasts,” a previously unknown cytotoxic glandular cell type in regenerative planarian flatworms. Ruptoblasts undergo an explosive cell death, “ruptosis,” triggered by activin, a multifunctional hormone acting as an inflammatory cytokine. Excessive activin—induced through protein injection, genetic chimerism, or bacterial infection—initiates ruptosis, discharging potent diffusible cytotoxic agents capable of eliminating nearby cells, bacteria, and even mammalian cells within minutes. Ruptoblast ablation suppresses inflammation but compromises bacterial clearance, highlighting their broad-spectrum immune functions. Mechanistically distinct from known cytotoxic and cell death mechanisms, the explosive nature of ruptosis relies on endoplasmic reticulum (ER)-derived calcium and cytoskeleton-dependent signal amplification. Ruptoblast-like cells appear conserved in diverse basal bilaterians, implying an ancient evolutionary origin. These findings unveil a strategy coupling hormonal regulation with immune defense and expand the landscape of evolutionary immune innovations.
