Kazuki Koizumi

Reduction in adverse reactions to platelets by the removal of plasma supernatant and resuspension in a new additive solution (M-sol).

BACKGROUND: Leukodepletion reduces but does not eliminate adverse reactions to platelet concentrate (PC). As an alternative strategy, plasma reduction or washing of platelets should be considered. However, the efficacy of this strategy is still unclear.

Hypogammaglobulinemia with a selective delayed recovery in memory B cells and an impaired isotype expression after rituximab administration as an adjuvant to autologous stem cell transplantation for non-Hodgkin lymphoma.

Abstract:  Objectives: Some studies have indicated patients who received rituximab as adjuvant to stem cell transplantation had an increased risk of developing severe hypogammaglobulinemia. The mechanism of this hypogammaglobulinemia is unknown, although investigators have hypothesized a further delay in the B‐cell recovery as one potential etiology. The aim of this study is to clarify the mechanism(s) of this hypogammaglobulinemia. Methods: A total of 14 patients with high‐risk CD20+ lymphoma underwent an autologous peripheral blood stem cell transplantation (APBSCT). After a hematological recovery, rituximab was given weekly for up to four doses as an adjuvant therapy. Results: After a median follow up of 33.5 months, we found six patients (group A) who had hypogammaglobulinemia, while the eight other patients (group B) had normal serum immunoglobulin levels. A phenotypical analysis revealed that group A patients had already achieved B‐cell recovery. However, we found a severe delay in the recovery of CD27+ memory B cells, especially in the IgD−/CD27+ switched populations in group A, but CD27 negative naive B‐cells reverted to a normal range in both groups. Consistent with this, reverse transcriptase‐polymerase chain reaction studies with peripheral blood mononuclear cells revealed that most patients in group A lacked more than two classes of isotype transcripts. Conclusions: Abnormal repertoires and impaired isotype expression are seen in patients with common variable immunodeficiency, these data suggested that rituximab after APBSCT can affect not only the B‐cell quantities, but also the recovery of the B‐cell repertoires.

A possible role for lamivudine as prophylaxis against hepatitis B reactivation in carriers of hepatitis B who undergo chemotherapy and autologous peripheral blood stem cell transplantation for non-Hodgkin's lymphoma

Hepatitis B virus (HBV) reactivation, a well-known complication in immunosuppressed patients, can give rise to acute hepatitis and even fatal fulminant hepatitis. Three Japanese males with non-Hodgkins lymphoma (NHL) who were carriers of HBV received high-dose chemotherapy followed by autologous peripheral blood stem cell transplantation (PBSCT). To prevent HBV reactivation, all received oral lamivudine (150 mg/day), a nucleoside analogue, at the start of chemotherapy. All were treated at full-dose intensity, including corticosteroids, without modification of treatment regimens. All three patients completed the total course of chemotherapy and PBSCT, with no signs of HBV reactivation. Peripheral blood stem cell (PBSC) harvests and hematological recoveries after transplantation were not affected by lamivudine, which was continued for at least 16 weeks after transplantation. HBV-DNA and DNA polymerase levels remained negative/normal after discontinuation of lamivudine. Lamivudine effectively inhibits HBV replication and has few serious adverse effects, particularly those related to hematopoiesis. Thus, prophylactic use of lamivudine from initiation of chemotherapy deserves consideration in the treatment of HBV carriers who require immunosuppressive chemotherapy, and may prevent HBV reactivation. Bone Marrow Transplantation (2001) 27, 433–436.

Effective high-dose chemotherapy followed by autologous peripheral blood stem cell transplantation in a patient with the aggressive form of cytophagic histiocytic panniculitis

A 20-year-old Japanese man developed generalized, subcutaneous, painless nodules, fever, abnormal liver function, serosal effusions, hepatosplenomegaly, lymphadenopathy and anemia. Skin biopsies revealed lobular panniculitis with a morphologically benign histiocytic infiltration and prominent phagocytosis. Atypical T lymphocytes were also present in the skin and liver. The diagnosis given was aggressive cytophagic histiocytic panniculitis (CHP) or aggressive subcutaneous panniculitic T cell lymphoma (SPTCL). He received cyclophosphamide, doxorubicin, and vincristine on day 1, prednisolone on days 1–5, and etoposide on days 1, 3 and 5 (CHOP-E), with the support of granulocyte colony-stimulating factor. This regimen was repeated every 2 weeks and complete clinical remission (CCR) was attained after three cycles of CHOP-E. As the clinical course of aggressive CHP is recurrent and often fatal, he was given high-dose chemotherapy followed by autologous peripheral blood stem cell transplantation (APBSCT), after five cycles of CHOP-E. He has remained in CCR for 12 months after APBSCT. High-dose chemotherapy followed by APBSCT is considered to be one of the most beneficial therapies for patients with aggressive CHP and aggressive phase SPTCL.

Tumor necrosis factor-α inhibits generation of glycophorin A+ cells by CD34+ cells

Abstract Objective The inhibitory effects of tumor necrosis factor-α (TNF-α) on cytokine-induced proliferation and differentiation of normal human erythroid progenitors have been characterized extensively, yet little is known about the maturation level of erythroid progenitors that are sensitive to TNF-α or of the expression of TNF receptors (TNFRs) in erythroid lineage. The aim of this study was to determine the extent to which human erythroid progenitor cells are sensitive to TNF-α, and to relate this to the expression of TNFRs in the erythroid lineage. Materials and Methods Highly purified human CD34 + cells underwent erythroid differentiation, with or without TNF-α. We used colony assay as well as a method by which colony-forming unit-erythroid (CFU-E) and glycophorin A (GPA; a specific marker for erythroid lineage) positive cells can be generated in liquid phase from purified human CD34 + cells in the presence of multiple cytokines, including stem cell factor (SCF), interleukin-3 (IL-3), and erythropoietin (EPO). During erythroid differentiation of CD34 + cells, TNFRs expression were monitored. Results TNF-α inhibited the generation of GPA + cells by CD34 + cells as well as the proliferative capacity of GPA + cells supported by EPO, IL-3, and SCF. Erythroid progenitors became resistant to the inhibitory effect of TNF-α as they matured. The detectable expression of TNFR-I was transient in the early phase of erythroid differentiation, whereas TNFR-II was expressed through the entire course of erythroid differentiation of CD34 + cells. Conclusions TNF-α suppresses erythropoiesis by inhibiting the generation of GPA + cells derived from CD34 + cells as well as by inhibiting the proliferative capacity of GPA + cells. Although the presence of TNFRs does not directly indicate that the receptor(s) mediates death signaling, altered expression of TNFRs depending on the level of maturation may imply altered sensitivities to TNF-α in various stage of erythroid progenitors.

Delayed redistribution of CD27, CD40 and CD80 positive B cells and the impaired in vitro immunoglobulin production in patients with non-Hodgkin lymphoma after rituximab treatment as an adjuvant to autologous stem cell transplantation

Recent studies have indicated that patients who received rituximab as an adjuvant to stem cell transplantation (SCT) demonstrated an increased risk of developing severe hypogammaglobulinaemia, which was found to be a result of delayed recovery of CD27 positive memory B cells and impaired isotype expression. It appears that rituximab influences both the quantity and quality of B‐cell redistribution. Precisely how the B‐cell repertoire regenerates after anti‐CD20‐mediated transient B‐cell depletion in patients with non‐Hodgkin lymphoma (NHL) remains to be elucidated. This study performed a phenotypical analysis of B cells in 17 NHL patients who received rituximab as an adjuvant to autologous SCT. The median period after final administration of rituximab was 36 months (range, 12–43 months). Surface antigen expression of CD27, CD40 and CD80 in NHL patients was statistically significantly different from healthy controls (n = 14). Moreover, B cells from NHL patients showed significantly impaired IgG and IgA production upon engagement of surface immunoglobulin receptors in the presence of interleukin (IL)‐2, IL‐10 and CD40 ligand in comparison with samples from healthy controls. The delayed recovery of memory B cells with an abnormal cell marker expression and function demonstrates that naive B cells may fail to differentiate into plasma cells, resulting in hypogammaglobulinaemia after autologous SCT and rituximab therapy.

A rapid nylon-fiber syringe system to deplete CD14+ cells for positive selection of human blood CD34+ cells. Use of immunomagnetic microspheres.

To achieve a rapid and an efficient purification of CD34+ cells, we devised a nylon-fiber syringe (NF-S) and we manipulated it to deplete adherent cells from normal human blood mononuclear cells (MN cells). The cells processed by NF-S were further purified as the CD34+ fraction, using CD34 monoclonal antibody, immunomagnetic microspheres and chymopapain treatment to detach the microspheres. When steady-state human peripheral blood MN cells were processed by NF-S at 24°C for 5 min, the frequency of monocytes (CD14+ cells) significantly decreased from 22.0 ± 5.2% to 2.5 ± 0.4%, with a 73% recovery of CD34+ cells. The subsequent immunomagnetic positive selection achieved preparations of 91 ± 8% pure CD34+ cells with a 86 ± 23% yield. The overall yield of CD34+ cells was 44 ± 11%, and the time required for all procedures was 5 h. There was a tight and an inverse correlation (P < 0.0001) between the frequency of cd14+ cells in the initial cell population and the purity of CD34+ cells in the final preparation. A recommended frequency of CD14+ cells for achieving preparations of over 90% pure CD34+ cells was less than 4.4%. When combining NF-S and immunomagnetic microspheres, efficient bench-top separation of CD34+ cells in steady-state peripheral blood can be done in any laboratory, and fluorescence- activated cell-sorting is not required.

Stem cell factor prevents Fas-mediated apoptosis of human erythroid precursor cells with Src-family kinase dependency

The Fas ligand (Fas-L) expressed on mature erythroblasts may induce apoptosis of more immature erythroid cells that express Fas, whereas stem cell factor (SCF) may prevent Fas-mediated cell death in hematopoietic progenitor cells. The manner in which SCF prevents Fas-mediated cell death still is unclear. Given the essential role of SCF and the potentially important involvement of the Fas/Fas-L system in the development of erythrocytes, we studied mechanisms related to SCF prevention of Fas-mediated apoptosis. We used primary cultured human erythroid colony-forming cells (ECFC) derived from CD34+ cells and enriched glycophorin A positive (GPA+) c-kit+ cells in ECFC. Apoptosis of ECFC was induced by an Fas-L mimetic monoclonal antibody CH11. DNA fragmentation and the activation of caspase-3 and caspase-8 were measured using commercially available kits. Characterization of expanded cells was performed using multiparameter flow cytometry. Lyn kinase activity was measured by enolase kinase assays. SCF inhibited the CH11-induced DNA fragmentation of ECFC as well as enriched GPA+ c-kit+ cells in ECFC, but not those of GPA+ c-kit- cells. SCF also inhibited the activation of caspase-3 and caspase-8, without downregulation of the surface expression of Fas, suggesting that SCF prevents apoptosis through uncoupling of Fas ligation from subsequent caspase activation. PP2, a specific inhibitor of Src-family kinases, antagonized the effects of SCF in preventing Fas-mediated apoptosis. We propose that SCF prevents Fas-mediated apoptosis of erythroid progenitor cells in a manner dependent on the activity of Src-family tyrosine kinases. We also identified active Lyn in erythroid cells. These data suggest the presence of a novel Src-family-dependent function of SCF in the development of erythrocytes.

STEM CELL FACTOR PROTECTS C-KIT+ HUMAN PRIMARY ERYTHROID CELLS FROM APOPTOSIS

OBJECTIVE It has been reported that stem cell factor (SCF) promotes cell survival in primary cultured human erythroid colony-forming cells (ECFC). Given the heterogeneous nature of ECFC, which may affect interpretation of the data, we purified c-kit+ ECFC and investigated the specificity and mechanisms of the anti-apoptotic effects of SCF on these cells. MATERIALS AND METHODS Glycophorin A+ (GPA+) c-kit+ cells were purified from primary cultured ECFC derived from purified human CD34+ cells. The GPA+c-kit- and nonerythroid cells were generated from the same CD34+ cells. Apoptosis of ECFC was investigated in the absence or presence of SCF and erythropoietin (EPO) in serum-free medium. DNA fragmentation was measured with enzyme linked immunosorbent assay for oligonucleosome-sized DNA, gel electrophoresis, and annexin V labeling. Characterization of expanded cells and enriched cells was performed using multiparameter flow cytometry. For Akt assay, cells were lysed and the cleared lysates subjected to SDS-PAGE followed by Western blotting. RESULTS In GPA+c-kit+ cells, deprivation of cytokine caused rapid DNA fragmentation within 4 hours that reached a maximum at 6 hours. This was partially but clearly prevented by SCF or EPO. In contrast, no significant DNA fragmentation was seen in GPA+c-kit- and nonerythroid cells within 24 hours. PP2, a specific Src family kinase inhibitor, but not its inactive analogue PP3, reversed the anti-apoptotic effects of SCF. PP2 also inhibited SCF-induced phosphorylation of Akt. CONCLUSION These data indicate that SCF protects purified human GPA+c-kit+ cells from apoptosis and suggest that kit-mediated Src kinase activation is involved in Akt activation and cell survival.

Proliferation and differentiation of myelodysplastic CD34+ cells in serum-free medium: response to individual colony-stimulating factors.

Summary. The presence of serum or contaminant cells may alter clonal development of haematopoietic progenitor cells in vitro. To investigate the pathogenesis of myelodysplastic syndromes (MDS), marrow progenitor cells from 13 MDS patients were highly purified using monoclonal antibodies including CD34 and immunomagnetic microspheres. The cells positive for CD34 in the purified cells were in the range from 87% to 98%. These purified cells were cultured in serum‐free medium with individual colony stimulating factors (CSFs) to investigate whether CD34+ cells from MDS patients have abnormal responses to individual CSFs. Dose response experiments with the purified CD34+ cells and recombinant human macrophage‐CSF (rM‐CSF), granulocyte‐CSF (rG‐CSF), granulocyte/macrophage‐CSF (rGM‐CSF), interleukin‐3 (rIL‐3) or erythropoietin (rEP) were performed in serum‐free fibrin clots in 11 patients. Five patients showed a diminished response to rG‐CSF and one patient to rEP. In the remaining six patients the purified CD34+ cells did not respond to a stimulation of any individual CSFs. The results indicate that the progenitor cell growth abnormalities in these disorders involve a defect in the capacity of progenitor cells to respond to stimulation with G‐CSF, and present direct evidence for the manner in which myelodysplastic CD34+ cells are impaired.