Predictors for successful PBSC collection on the fourth day of G‐CSF‐induced mobilization in allogeneic stem cell donors

Peripheral blood stem cells (PBSCs) used for allogeneic transplantation are collected by apheresis after pre‐treatment of donors with G‐CSF. Using modern apheresis devices stem cells can be collected more efficiently. It was studied whether collection on the 4th instead of the 5th day after initiation of G‐CSF treatment might be feasible. Stem cell yields that could have been collected on day 4 were calculated in two cohorts treated with 10 µg/kg G‐CSF once daily (n = 106, cohort I) or 5 µg/kg twice daily schedule (n = 85, cohort II). Harvests were predicted using the median collection efficiency (CE) of the apheresis machine and regarded successful when > 5.0 x10⁶ CD34^+/kg recipient body weight. Successful harvests at day 4 could have been obtained in only 22.6% and 41.2% of donors in cohort I and II respectively, while the expected successful collections on day 5 were 55.7% and 76.5%. Individual donor factors that correlated with a successful harvest on day 4 were weight, BMI, age, ratio donor/recipient weight and total G‐CSF dose in cohort I, whereas ratio donor/recipient weight was the only significant predictor in cohort II. Donor weight, BMI and total G‐CSF dose correlated positively with CD34⁺ values in the blood on day 4 in all donors. However, donor characteristics were not able to be used as strong predictors in daily practice. In conclusion, PBSC collection on day 4 will not result in a successful harvest in most stem cell donors, however using a twice daily G‐CSF scheme increases the yield.     

von Willebrand factor binds to the surface of dendritic cells and modulates peptide presentation of factor VIII

It has been proposed that von Willebrand factor might affect factor VIII immunogenicity by reducing factor VIII uptake by antigen presenting cells. Here we investigate the interaction of recombinant von Willebrand factor with immature monocyte-derived dendritic cells using flow cytometry and confocal microscopy. Surprisingly, von Willebrand factor was not internalized by immature dendritic cells, but remained bound to the cell surface. As von Willebrand factor reduces the uptake of factor VIII, we investigated the repertoire of factor VIII presented peptides when in complex with von Willebrand factor. Interestingly, factor VIII-derived peptides were still abundantly presented on major histocompatibility complex class II molecules, even though a reduction of factor VIII uptake by immature dendritic cells was observed. Inspection of peptide profiles from 5 different donors showed that different core factor VIII peptide sequences were presented upon incubation with factor VIII/von Willebrand factor complex when compared to factor VIII alone. No von Willebrand factor peptides were detected when immature dendritic cells were pulsed with different concentrations of von Willebrand factor, confirming lack of von Willebrand factor endocytosis. Several von Willebrand factor derived peptides were recovered when cells were pulsed with von Willebrand factor/factor VIII complex, suggesting that factor VIII promotes endocytosis of small amounts of von Willebrand factor by immature dendritic cells. Taken together, our results establish that von Willebrand factor is poorly internalized by immature dendritic cells. We also show that von Willebrand factor modulates the internalization and presentation of factor VIII-derived peptides on major histocompatibility complex class II.     

C-Terminal Peptide of γ-Enolase Impairs Amyloid-β-Induced Apoptosis Through p75NTR Signaling

γ-Enolase acts as a neurotrophic-like factor promoting growth, differentiation, survival and regeneration of neurons. It is shown in this study to exert a protective effect against amyloid-β-peptide (Aβ)-induced neurotoxicity in rat pheochromocytoma PC12 cells. Aβ-induced toxicity was abolished in the presence of the active C-terminal peptide of γ-enolase (γ-Eno) as measured by cell viability, lactate dehydrogenase release, sub-G1 cell population, intracellular reactive oxygen species, mitochondrial functions and apoptotic morphology. γ-Eno caused downregulation of the pro-apoptotic protein Bax and upregulation of the anti-apoptotic protein Bcl-2, as well as reduced caspase-3 activation. Exposure to Aβ increased surface expression of p75 neurotrophin receptor (p75^NTR), and the increase was abolished in the presence of γ-Eno peptide. Further, pretreatment with γ-Eno suppressed the activation of mitogen-activated protein kinases p38 and Jun-N-terminal kinase, which are p75^NTR downstream effectors in apoptotic signaling. Moreover, Aβ triggered γ-enolase co-immunoprecipitation with p75^NTR as well as their strong association in the perimembrane region as shown by confocal microscopy, which further supports the interaction between these two proteins in cells insulted by Aβ peptide. Our results indicate the possible use of γ-enolase C-terminal peptide for treating or preventing Alzheimer’s disease.     

γ-Catenin-Dependent Signals Maintain BCR-ABL1+ B Cell Acute Lymphoblastic Leukemia

1. Download high-res image (135KB)
2. Download full-size image