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Analysis of factors affecting PBPC collection in low-weight children with malignant disorders.

BACKGROUND
PBPC collection in children weighing </=25 kg is hampered by technical and clinical problems related to vascular access, low total blood volume, anticoagulation, side effects, and psychological impact. The aim of this study was to analyze several clinical and technical factors, other than pre-apheresis CD34(+) count, that may affect PBPC collection in these low-weight children.


METHODS
Data from 88 leukaphereses performed in 45 children were analyzed, including pre-apheresis CD34(+) cell count, COBE Spectra software (version 4.7 versus 6.0), apheresis volume [standard versus large-volume leukapheresis (LVL)] and patient's diagnosis, age, weight and sex.


RESULTS
The median number of PBPC collected was 6.68 mononuclear cells (MNC)x10(8)/kg (range 2.36-19.05) and 1.69 CD34(+) cellsx10(6)/kg (range 0.08-13.79). Multivariate analysis showed that factors independently associated with the CD34(+) cell yield per apheresis were pre-apheresis CD34(+) cell count (P<0.001), diagnosis (P=0.008) and apheresis volume (P=0.009). Recruitment of CD34(+) cells was also independently affected by the apheresis volume, being higher in the LVL group (P=0.008).


DISCUSSION
We have demonstrated that, apart from the well-known influence of the pre-apheresis CD34(+) cell count, two other factors have a major impact on the CD34(+) cell yield: patient's diagnosis and apheresis volume. In addition, taking into account that side effects were mild and tolerable, we have confirmed that LVL is a safe and effective procedure in children </=25 kg, and that AutoPBSC software could be reliably used in these patients, provided that an experienced team performs the procedure.