[Neutrophil disorders: diagnosis and hematopoietic stem cell transplantation]

Neutrophil disorders are classified into abnormal neutrophil function and granulopoiesis. The identification of genetic defects causing neutropenia and neutrophil dysfunction has revealed the mechanisms controlling myeloid differentiation and their functions. The International Union of Immunological Societies of Primary Immunodeficiencies represents the most current catalog of approximately 30 neutrophil disorders. In this report, we show the progress made in studies of the pathophysiology and treatment of these disorders, focusing on chronic granulomatous disease (CGD) and severe congenital neutropenia (SCN). Hematopoietic stem cell transplantation (HSCT) is the only available curative therapy for CGD and SCN. However, the use of HSCT as treatment for both diseases is limited by transplant-related mortality (TRM) because of active infections and intractable inflammatory complications. Recently, reduced-intensity conditioning regimens have been introduced to minimize the TRM and the late adverse effects of HSCT for both diseases. The results of HSCT using the RIC regimen for 40 patients with CGD and SCN in Hiroshima University Hospital are summarized herein. Determining the optimal line of treatment will require further accumulation to cases to refine HSCT for both diseases.