Mobilization and collection of peripheral blood stem cells: guidelines for blood volume to process, based on CD34-positive blood cell count in adults and children.

We report 189 mobilizations and 489 collections of peripheral blood stem cells (PBSC) performed in 139 autologous transplantation patients and in 28 donors for allogeneic transplantations whose ages ranged from 2-68 years. We observed a correlation (P < .001; Pearson's coefficient 0.64) between CD34-positive cells and granulocyte-macrophage colony-forming units examined to estimate PBSC. In a subset of 287 collections (97 adults and 49 children) we obtained peripheral blood (PB) CD34-positive cell counts at 2 to 4 hours before leukapheresis. We noted a correlation between PB CD34-positive cell counts before leukapheresis and the number of CD34-positive cells per kilogram of body weight collected in the whole apheresis of the day (P < .001; Pearson's coefficient 0.82). An even better correlation was obtained between PB CD34-positive cells preapheresis and the yield of each individual blood volume (BV) processed (P < .001; Pearson's coefficient 0.87). Healthy donors and patients in each age group behaved similarly. In addition, the collection yield was greater among children than adults. These findings allowed us to develop a simple predictive model to estimate the BV to process for a target dose of CD34-positive cells per kilogram, based on the level of PBSC before apheresis in children and adults.

Increased susceptibility of microcytic red blood cells to in vitro oxidative stress.

Oxidative damage to erythrocytes in thalassaemia has been related to generation of free radicals by an excess of denaturated alpha- or beta-globin chains, intracellular iron overload and low concentration of normal haemoglobin (HGB). Two good indicators of such oxidative damage are the high red blood cell (RBC) malonyldialdehyde (MDA) production detected following exogenous oxidant stress and the decrease of pyrimidine 5'-nucleotidase (P5N), the most sensitive enzyme to SH-group damage in vivo. Conflicting data, however, have so far accumulated in the literature concerning differences in oxidative damage between the different forms of thalassaemia and iron deficiency anaemia (IDA). In the present study, oxidative susceptibility, as defined by the production of MDA in vitro and antioxidant capacity, as measured by the activity of RBC glutathione peroxidase (GPx), superoxide dismutase (SOD) and by reduced glutathione (GSH), have been studied in microcytic RBCs from patients with beta-thalassaemia trait, Spanish (delta beta) zero-thalassaemia heterozygotes (delta beta-thalassaemia trait) and iron deficiency anaemia (IDA). The results are consistent with the existence of significant differences in the severity and pattern of oxidative stress susceptibility between beta-thalassaemia trait (increased MDA production and higher SOD and GPx activities) and the other two forms of microcytosis (delta beta thalassaemia trait and IDA). Furthermore, the finding of normal P5' N activity in delta beta thalassaemia trait, gives further support to the less intense peroxidative environment of RBCs in this form of thalassaemia when compared to beta-thalassaemia trait, characterized by acquired RBC P5' N deficiency due to oxidative damage.