Blood can be used as source material for a variety of biological investigations. The nature of the study dictates how the blood sample should be handled.
If you are attempting to identify pathogens or metastasizing tumor cells, extracting whole blood might be the only choice if there is no method to specifically capture the cells of interest. Red blood cells (RBCs), which can add a confounding factor, can be lysed using an isotonic NH4Cl solution (J Immunol Methods 1:273 (1972)), and the other cells present may be pelleted in a low-speed centrifugation step. This procedure has also been used for white blood cells (WBCs), but there is some question regarding how it affects WBC metabolism. For DNA investigations, this is probably of no consequence, but if the experiment is aimed at analyzing modulations in immune function, it would be advantageous to isolate buffy coat cells or specific white blood cells as soon after the blood draw as possible. For experiments looking at RNA contained in smaller carriers (e.g., protein complexes or exosomes), plasma or serum is the appropriate blood component to work with.
General Considerations When Working With Blood
|Whole (and Stabilized) Blood|
|White Blood Cells|