Myelofibrosis (MF) is characterized by increased circulating
hematopoietic progenitor cells (HPCs), abnormal
cytokine levels, and the
survival advantage of neoplastic progenitors over their normal counterparts, which leads to progressive disappearance of polyclonal
hematopoiesis. CD47 is a
surface glycoprotein with many functions, such as acting as a
phagocytosis inhibitor of the expressing
cell, that is increased in normal hematopoietic
stem and
progenitor cells mobilized into the
blood and several
human cancer-initiating
cells, such as in
acute myeloid leukemia. We compared CD47 expression in hematopoietic
stem and
progenitor cells of
patients with MF and controls and found it to be decreased in progenitors of MF. Exposure of control HPCs to the
cytokines transforming growth factor β and stromal-derived factor 1, which are important regulators of
hematopoietic stem cell cycling and are overexpressed in
patients with MF, did not modulate CD47 expression.