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HEMATOPOIESIS
From the Department of Immunoregulation/Research
Institute for Microbial Diseases and the Research Foundation for
Microbial Diseases, Osaka University; the Department of Hematology and
Oncology, Osaka University Medical School; Ikoma General Hospital,
Nara; Osaka Red Cross Hospital; Second Department of Internal Medicine,
Hyogo College of Medicine; Osaka Medical Center for Cancer; Asiya
Municipal Hospital, Hyogo; Southern Wakayama National Hospital; and
Osaka National Hospital, Japan.
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired
hematopoietic stem cell disorder characterized by clonal blood cells that are deficient in glycosylphosphatidylinositol-anchored proteins because of somatic mutations of the PIG-A gene. Many
patients with PNH have more than one PNH clone, but it is unclear
whether a single PNH clone remains dominant or minor clones eventually become dominant. Furthermore, it is unknown how many hematopoietic stem
cells (HSCs) sustain hematopoiesis and how long a single HSC can
support hematopoiesis in humans. To understand dynamics of HSCs,
we reanalyzed the PIG-A gene mutations in 9 patients 6 to
10 years after the previous analyses. The proportion of affected peripheral blood polymorphonuclear cells (PMNs) in each patient was
highly variable; it increased in 2 (from 50% and 65% to 98% and
97%, respectively), was stable in 4 (changed less than 20%), and
diminished in 3 (94%, 99%, and 98% to 33%, 57%, and 43%,
respectively) patients. The complexity of these results reflects the
high variability of the clinical course of PNH. In all patients, the
previously predominant clone was still present and dominant. Therefore,
one stem cell clone can sustain hematopoiesis for 6 to 10 years in patients with PNH. Two patients whose affected PMNs decreased because
of a decline of the predominant PNH clone and who have been followed up
for 24 and 31 years now have an aplastic condition, suggesting that
aplasia is a terminal feature of PNH. This article has been cited by other articles:
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| Copyright © 2002 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||