Blood, 1 April 2003, Vol. 101, No. 7, pp. 2450-2450
New insights into chronic idiopathic neutropenia
Chronic idiopathic neutropenia (CIN) is a relatively
common disorder predominantly affecting women. Blood neutrophil
counts are less than 1.5 × 109/L, but other
blood cell counts are normal. Bone marrow examination, if performed,
usually shows only a modest reduction in metamyelocytes and
neutrophils. In general, the severity of the neutropenia does not
worsen, and patients do not evolve to develop systemic lupus erythematosus, aplastic anemia, or leukemia. If blood neutrophil counts
are less than 0.5 × 109/L, fever and minor infections
are common, and treatment with recombinant G-CSF can be helpful.
In this issue Papadaki and colleagues (page 2591) provide
valuable new insights suggesting that the mechanism for neutropenia in
CIN is similar to that in Felty syndrome, that is, accelerated apoptosis of neutrophil precursors due to excessive production of
interferon gamma and tumor necrosis by immune cells in the bone marrow.
In their study of 28 women and 4 men, they observed that the
percentages of marrow CD34+ and
CD34+/CD33+ cells were reduced and a higher
than normal percentage of the CD34+ cells were
apoptotic. Separated CD34+ cells had reduced
colony-forming capacity and grew less well in long-term cultures than
similar normal cells. Supernates from these long-term cultures
contained increased amounts of proinflammatory cytokines known to
inhibit myelopoiesis.
This paper from Crete is remarkable for the thoroughness of the
investigations, the long-term follow-up of the patients, and the new
insights it provides about a heretofore poorly understood entity. It
helps us connect idiopathic neutropenia to the autoimmune disorders,
that is, lupus erythematosus and rheumatoid arthritis, by finding a
similar mechanism for neutropenia. It also adds another condition to
the growing list of diseases for which accelerated apoptosis of
progenitor cells is the underlying cellular mechanism of neutropenia.
David C. Dale
University of
Washington
