title: Platelet derived growth factor receptor-beta (PDGFRβ) expression is limited to activated stromal cells in the bone marrow and shows a strong correlation with the grade of myelofibrosis.
abstract: Platelet derived growth factor receptor (PDGFR) is a membrane tyrosine-kinase receptor required for fibroblast activation in stromal proliferations. In order to assess the role of PDGFR in myelofibrosis (MF) we determined in 60 bone marrow biopsies the occurrence and distribution of its α and β subunits in normal and fibrotic bone marrow stroma using immunohistochemistry, and compared this with the grade of MF determined by Gömöri's silver impregnation. PDGF receptor subunits were found to be differentially expressed in the marrow parenchyma. PDGFRα expression identified megakaryocytes, endosteal and endothelial cells while PDGFRβ was virtually absent from inter-trabecular spaces in normal marrow. Activated fibroblasts characteristic for MF intensely expressed PDGFRβ but only a moderate increase in PDGFRα expression was seen. Semi-quantitative PDGFRβ immunoreactivity scores correlated well with the grade of MF in the vast majority of the MF cases (Spearman r= 0.83). Altogether, 21/60 (35.0%) cases showed a relative increase of PDGFRβ expression, compared to the MF grade, suggesting that increased stromal PDGFRβ expression occurs early and precedes reticulin and collagen fiber production during fibroblast activation. In conclusion, bone marrow PDGFRβ expression closely correlates with the grade of MF. Increased immunoreactivity for PDGFRβ occurs already in the prefibrotic stage of the disease and might allow a functional classification of the bone marrow stromal reaction.
authors.affiliation: Department of Pathology, University of Debrecen, Nagyerdei krt. 98, 4032 Debrecen, Hungary.
authors.forename: Judit
authors.initials: J
authors.lastname: Bedekovics
authors.forename: Attila
authors.initials: A
authors.lastname: Kiss
authors.forename: Lívia
authors.initials: L
authors.lastname: Beke
authors.forename: Katalin
authors.initials: K
authors.lastname: Károlyi
authors.forename: Gábor
authors.initials: G
authors.lastname: Méhes
mesh_terms: D018952:Antigens, CD34 / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D059630:Mesenchymal Stem Cells / Q000737:chemistry*; D055728:Primary Myelofibrosis / Q000378:metabolism / Q000473:pathology*; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000032:analysis / Q000502:physiology*
chemical_list: D018952:Antigens, CD34; D020797:Receptor, Platelet-Derived Growth Factor beta