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MHC II-expressing bone marrow megakaryocytes are noncanonical antigen-presenting cells and activate CD4(+) T cells ex vivo.
Cell Reports · · Journal Article
Camacho, Wang + more
Abstract ↗AI summary
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About 20% of bone marrow megakaryocytes express MHC II and co-stimulatory receptors, process antigen, and activate CD4+ T cells ex vivo in an MHC II-dependent manner.
- Why it matters: Professional antigen-presenting cells are well studied, but the bone marrow niche also contains atypical immune-capable cells whose roles in CD4+ T regulation remain unclear.
- What they did: The study quantified MHC II+ MKs (~20%) and showed antigen presentation and T cell activation ex vivo, with immunopeptidomics confirming MK MHC II peptide occupancy in vivo.
- The result: MK/T cell interactions induced TGF-β1 secretion and promoted induced Treg differentiation, while MK-targeted MHC II deletion altered TLR responses and reduced bone marrow TGF-β1.
The findingWhy it mattersWhat they didThe result
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