Extraction of RNA from Fresh and Frozen Blood

Whole blood contains nucleated white cells that constitute an easily accessible source from which RNA can be extracted, without the need for prior homogemzation as is necessary with solid tissues. However, blood is a particularly problematic tissue from which to isolate RNA because RNA is extremely prone to degradation by ribonucleases, of which red cells are a rich source. Furthermore, blood constituents or their derivatives may inhibit PCR reactions (1 ) RNA extraction from blood is therefore usually more successful if the nucleated white cells are first isolated from the red cells. As with extraction from other tissues, it is important to minimize degradation by following the appropriate recommendations for handling RNA, as detailed in the methodology below.