Enrichment of cell subpopulations applying automated MACS technique: purity, recovery and applicability for PCR-based chimerism analysis.

Enrichment of cell subpopulations is a prerequisite for lineage-specific chimerism analysis (LCA), a frequent approach in follow-up after allo-SCT. An efficient enrichment technique is Magnetic Cell Sorting (MACS) using the AutoMACS separator. However, evaluation of purity, recovery and applicability for PCR-based chimerism analysis of MACS-enriched subpopulations from post-transplant peripheral blood, providing reduced cell numbers and/or unbalanced proportions of subpopulations, is currently unavailable. We performed enrichment of CD3-, CD14-, CD15-, CD19- and CD56-positive subpopulations using 'Whole Blood MicroBeads' and AutoMACS separator in 137 prospectively collected peripheral blood samples from 15 paediatric patients after allo-CD3-/CD19-depleted SCT. Purity was assessed by immune phenotyping. Recovery and applicability for chimerism analysis was evaluated. Excellent purity >90% was achieved in CD14-, CD15-positive cells in 81%, 95% of the isolates and in 86% of CD3 and CD19 isolates, if ACC was >400 cells per mul. Median purity of CD56-positive isolates was 78.9%. Recovery >90% was between 93 (CD56) and 37% (CD15). Conventional and real-time PCR-based chimerism analysis was feasible in virtually all samples. Isolation of cell subpopulations by automated cell enrichment in post-transplant peripheral blood is feasible and fast providing excellent purity and recovery for routine lineage-specific chimerism analysis.