G. Malpuech

Kinetics of hematopoietic progenitor cell release induced by G-CSF-alone in children with solid tumors and leukemias

The kinetics of peripheral blood progenitor cell (PBPC) release induced by G-CSF-alone at 10 μg/kg/day were monitored daily in 42 children with solid tumors and leukemias. Median 16- and 27-fold enrichment of circulating CD34+ cells and granulocyte–macrophage colony-forming units (CFU-GM) was noted with peak values occurring after the 4th or the 5th G-CSF dose. Individual values of PBCD34+ cell levels in patients with solid tumors were not significantly different after the 4th and after the 5th dose. The day-of-collection PBCD34+ cell concentration was related to the harvested CD34+ cell (P = 0.0001) and CFU-GM numbers (P = 0.0001). No correlations were found between PBPC enrichment and either patient age, body weight, diagnosis or pre-mobilization treatment duration. The median numbers of 1.1 × 106 CD34+ cells/kg and 28.1 × 104 CFU-GM/kg were derived from one patient’s blood volume processed. Nineteen patients received G-CSF-alone primed grafts and had successful engraftment. Our data indicate that in 88% of children a single standard leukapheresis is sufficient to obtain a minimum graft (2 × 106 CD34+ cell and/or 10 × 104 CGU-GM per kg) whether undertaken after the 4th dose of G-CSF or the 5th.

Use of G‐CSF alone to mobilize peripheral blood stem cells for collection from children

Summary We report the data of 19 children with neuroblastoma (NB) or Ewings sarcoma (EW) who had peripheral blood stem cells (PBSCs) harvested after mobilization by: (1) cyclophosphamide (CY) + etoposide + G‐CSF, (2) CY+GM‐CSF, or (3) G‐CSF alon. There were no consistent differences in the number of PBSCs collected following these three different mobilization regimens as assessed by CFU‐GM. 17 patients were reinfused with PBSCs after myeloablative therapy and had successful haemopoietic recovery. These results show that in children with solid tumours such as NB or EW a sufficient number of PBSCs can be collected after G‐CSF alone, and that PBSCs collected following stimulation by G‐CSF alone are as effective in reconstituting haemopoiesis as those collected after mobilizing chemotherapy + HGFs.

Hypomagensemia with secondary hypocalcemia in a female with balanced X;9 translocation: mapping of the Xp22 chromosome breakpoint

Magnesium-dependent hypocalcaemia (HSH), a rare inherited disease, is caused by selective disorders of magnesium absorption. Both X-linked and autosomal recessive modes of inheritance have been reported for HSH; this suggests a genetically heterogeneous condition. A balanced de novo t(X;9)(p22;q12) translocation has been reported in a female manifesting hypomagnesemia with secondary hypocalcemia. In a lymphoblastoid cell line, derived from this patient, the normal X chromosome is preferentially inactivated, suggesting that the patients phenotype is caused by disruption of an HSH gene in Xp22. In an attempt to define more precisely the position of the X breakpoint, we have constructed a hybrid cell line retaining the der(X)(Xqter-Xp22.2::9q12-9qter) in the absence of the der(9) and the normal X chromosome. Southern blot analysis of this hybrid and in situ hybridization on metaphase chromosomes have localized the breakpoint between DXS16 and the cluster (DXS207, DXS43), in Xp22.2. Thus, if a gene involved in HSH resides at or near the translocation breakpoint, our findings should greatly facilitate its isolation.

Septicémie à Malassezia furfur au décours d'une greffe de moelle

BACKGROUND: Systemic Malassezia furfur (Mf) infections are only seen in neonates and immunocompromised patients. CASE REPORT: A 2-year-8-month-old boy was given chemotherapy for mediastinal T cell lymphoma. Meningeal relapse supervened 10 months later, requiring polychemotherapy plus CNS irradiation followed by bone marrow transplantation. Three days after transplantation, fever associated with neutropenia required administration of ceftazidime, amikacin, vancomycin plus acyclovir followed by amphotericin B, cefotaxime plus erythromycin. Blood cultures were negative, but blood swears showed yeasts into polynuclear cells after cytocentrifugation; these yeasts were also present in the central catheter removed after a few days course of amphotericin B, flucytosine plus fluconazole. The patient was then given GM-CSF subcutaneously (5 micrograms/kg/day), followed by progressive correction of aplasia and cure of the Mf infection. CONCLUSION: This is a new case of systemic Mf infection seen in an immunocompromised child receiving parenteral nutrition with lipids.

Two-step immunoablative treatment with autologous peripheral blood CD34(+) cell transplantation in an 8-year-old boy with autoimmune haemolytic anaemia.

Life‐threatening haemolysis in children with autoimmune haemolytic anaemia (AIHA) occurs rarely. Many cases of severe autoimmune disease are currently treated with immunosuppressive high‐dose chemotherapy and autograft. We report here a case of a child with severe AIHA who did not respond to conventional treatments, but was cured with an autologous peripheral blood CD34+ cell transplantation. After d 16 post autograft, no further red cell transfusions were required. At 20 months post autograft, haematological complete remission persists.