Resident bone marrow macrophages in idiopathic (primary) myelofibrosis (IMF): a histochemical and morphometric study on sequential trephine biopsies

A histochemical and morphometric study was performed on sequential bone marrow biopsies in 65 patients with idiopathic (primary) myelofibrosis (IMF) to quantify the resident-mature CD68(+) macrophages and a peculiar, so-called activated subpopulation. Statistical analysis revealed no significant correlations between number of macrophages, density of argyrophilic fibers and degree of myeloid metaplasia. Our results are reflecting in vitro findings on cytokine release, macrophage activation and their complex functional associations with myelofibrotic matrix formation. Macrophage growth is assumed to be related to a number of putative pathomechanisms including abnormal (upregulated) cytokine expression (PDGF, TGF-beta, IL-1), enhancement and activation by CSF-1 (M-CSF) and possibly also phagocytic stimulation. The latter feature may be triggered by increased degradation of senescent megakaryocytes, frequently occurring as endstages of growth factors-releasing fibrogenetic megakaryopoiesis. (C) 1999 Elsevier Science Ltd. All rights reserved.