Consistent with our findings, previous studies found a reduction of detected probes, lower gene expression signals and increased inter-individual variability as compared to PBMCs [7,8]. Because the main differences between PAX and PBMCs are the depletion of erythrocytes and reticulocytes from the latter, it is assumed that these differences are related to the abundant mRNA expression of members of the hemoglobin gene family [8,22-25]. Previous studies have shown that depletion of globin mRNA resulted in an increased number of detected probes, a decrease of variability and improved detection sensitivity for mRNAs from non-reticulocyte cell types [8,22-27] but we did not specifically test this option in the present study.
