Preanalytical stability of HIV-1 and HCV RNA: impact of storage and plasma separation from cells on blood donation testing by NAT

HCV RNA Testing of Plasma Samples from Cornea Donors: Suitability of Plasma Samples Stored at 4 °C for up to 8 Days

BACKGROUND

The HCV RNA testing of potential cornea donors frequently relies on blood samples stored pre mortem. The recommended storage time of maximum 72 h frequently excludes a significant fraction of donors.

METHODS

The influence of storage time of EDTA plasma samples at 4 °C on the viral load measured with the Roche HCV Quantitative Test vs. 2.0 was evaluated for 43 samples from HCV-positive individuals.

RESULTS

The mean reduction of the viral load after 4 °C storage for 6-8 days was 0.46 log₁₀ IU/ml (range +0.17 to -1.66 log₁₀ IU/ml). After 1-3 days a mean loss of 0.19 log₁₀ IU/ml (range +0.30 to -1.41 log₁₀ IU/ml) and after 3-5 days of 0.32 log₁₀ IU/ml (range +0.36 to -1.81 log₁₀ IU/ml) was observed. In 23.3% of samples, a viral load reduction ≥ 1 log₁₀ IU/ml (1.0-1.81 log₁₀ IU/ml) was found after prolonged storage (5-8 days). In none of the samples did the HCV load fall below the detection limit.

CONCLUSION

Plasma storage for up to 8 days can quantitatively reduce the HCV RNA load, yet has no influence on the reliability of a qualitative HCV RNA detection by this ultrasensitive test to determine the HCV status of serologically negative cornea donors.

Extracellular ATP and adenosine: The Yin and Yang in immune responses?

Extracellular adenosine 5'-triphosphate (ATP) and adenosine molecules are intimately involved in immune responses. ATP is mostly a pro-inflammatory molecule and is released during hypoxic condition and by necrotic cells, as well as by activated immune cells and endothelial cells. However, under certain conditions, for instance at low concentrations or at prolonged exposure, ATP may also have anti-inflammatory properties. Extracellular ATP can activate both P2X and P2Y purinergic receptors. Extracellular ATP can be hydrolyzed into adenosine in a two-step enzymatic process involving the ectonucleotidases CD39 (ecto-apyrase) and CD73. These enzymes are expressed by many cell types, including endothelial cells and immune cells. The counterpart of ATP is adenosine, which is produced by breakdown of intra- or extracellular ATP. Adenosine has mainly anti-inflammatory effects by binding to the adenosine, or P1, receptors (A1, A2A, A2B, and A3). These receptors are also expressed in many cells, including immune cells. The final effect of ATP and adenosine in immune responses depends on the fine regulatory balance between the 2 molecules. In the present review, we will discuss the current knowledge on the role of these 2 molecules in the immune responses.