Increased and pathologic emperipolesis of neutrophils within megakaryocytes associated with marrow fibrosis in GATA-1low mice

Lucia Centurione, Angela Di Baldassarre, Maria Zingariello, Domenico Bosco, Valentina Gatta, Rosa Alba Rana, Vincenzo Langella, Antonio Di Virgilio, Alessandro M. Vannucchi, Anna Rita Migliaccio

Research output: Contribution to journalArticlepeer-review

101 Scopus citations

Abstract

Deletion of megakaryocytic-specific regulatory sequences of GATA-1 (Gata1tm2Sho or GATA-1low mutation) results in severe thrombocytopenia, because of defective thrombocytopoiesis, and myelofibrosis. As documented here, the GATA-1low mutation blocks megakaryocytic maturation between stage I and II, resulting in accumulation of defective megakaryocytes (MKs) in the tissues of GATA-1low mice. The block in maturation includes failure to properly organize α granules because von Willebrand factor is barely detectable in mutant MKs, and P-selectin, although normally expressed, is found frequently associated with the demarcation membrane system (DMS) instead of within granules. Conversely, both von Willebrand factor and P-selectin are barely detectable in GATA-1low platelets. Mutant MKs are surrounded by numerous myeloperoxidase-positive neutrophils, some of which appear in the process to establish contact with MKs by fusing their membrane with those of the DMS. As a result, 16% (in spleen) to 34% (in marrow) of GATA-1low MKs contain 1 to 3 neutrophils embedded in a vacuolated cytoplasm. The neutrophil-embedded GATA-1low MKs have morphologic features (high electron density and negativity to TUNEL staining) compatible with those of cells dying from para-apoptosis. We suggest that such an increased and pathologic neutrophil emperipolesis may represent one of the mechanisms leading to myelofibrosis by releasing fibrogenic MK cytokines and neutrophil proteases in the microenvironment.

Original languageEnglish
Pages (from-to)3573-3580
Number of pages8
JournalBlood
Volume104
Issue number12
DOIs
StatePublished - 1 Dec 2004
Externally publishedYes

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