Gene expression profiling of human blood is becoming increasingly used in the pharmaceutical and diagnostic industries for the discovery and development of clinical biomarkers linked to human disease. The laboratory steps and equipment required to reproducibly isolate white blood cells (WBCs) not only increase the cost but also the elapsed time to RNA isolation.

The manipulations required and time to RNA isolation likely result in altered gene expression profiles. To mitigate this issue, methods have been developed to process whole blood prior to RNA isolation and gene expression analysis. The most useful microarray expression profiling data is generated from whole blood samples in which red blood cells (RBCs) are selectively pre-lysed and the RNA is subsequently purified. However, the abundance of globin mRNA transcripts in RBCs and reticulocytes masks the mRNA contributed by WBCs.

In this report, we compare microarray data from WBCs (the “gold standard” in terms of low globin mRNA contamination), unblocked whole blood and blood samples in which globin cDNA synthesis is blocked using a proprietary globin reduction protocol….

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