QuantiFERON–CMV is not available in the United States.
QuantiFERON–CMV is CE marked for commercial use in Europe

Search Results: Displaying all Blood Incubation and Plasma Harvesting (11)

Question Date Updated
What if 37°C incubation starts more than 16 hours after the time of blood collection? 2013 The Package Insert specifies that the 37°C blood incubation must commence within 16 hours of collection. Blood samples incubated more than 16 hours after collection are likely to exhibit a decreased IFN-ɣ response due to cellular breakdown (death), leading to loss of sensitivity and inaccurate results.
Can I incubate the blood collection tubes lying down? 2013 QuantiFERON-HCMV Blood Collection Tubes must be kept upright during incubation at 37°C.
Do I have to centrifuge the tubes before I can harvest the plasma? 2013 While it is recommended to centrifuge the tubes to assist with harvesting, it is possible to harvest the plasma from the tubes without centrifugation. Additional care is required to remove the plasma without disturbing the cells.
Do I have to centrifuge the tubes immediately after removal from incubator? 2013 QuantiFERON-HMCV Blood Collection Tubes may be held between 2°C and 27°C for up to 3 days before centrifugation or harvesting.
The gel plug hasn't moved during centrifugation. What should I do? 2013 After incubation of tubes at 37°C, the plasma is separated from the cells by centrifuging for 15 minutes at 2000 - 3000 RCF (g). The gel plug should move to separate the cells from the plasma. If this does not occur, the tubes should be re-centrifuged at a higher speed.
The plasma doesn't appear the colour it normally does. Is this OK? 2013 Plasma from the QuantiFERON-CMV Blood Collection Tubes can appear more red than usual but this is normal. It should be noted that the colour of plasma, even those without any red blood cell contamination, can vary from almost colourless to shades of yellow/pale brown; some plasma samples even have an opaque character. These qualities have not been found to affect QuantiFERON-CMV results.
Do I require a Class II Biohazard Cabinet in which to perform plasma harvesting? 2013 Ideally, all work with blood should be performed in a Biohazard Cabinet to minimize the risk of infection (eg HIV, Hepatitis-B) from potentially infectious blood samples. However, as long as aseptic techniques are used, plasma harvesting can be performed outside of a Biohazard cabinet. 'Safe Laboratory Practices' should be followed, including the use of protective clothing such as gloves, gown, safety eyewear etc, as suggested by relevant regulators.
When harvesting the plasma from above the sedimented red blood cells or gel plug, what volume do I need to remove? Is this important? 2013 As little as 100 µLof plasma is sufficient, as only 50 µL of plasma is required to perform the ELISA. (55 µL is required if a 1:10 dilution is tested well). 200 µL will leave sufficient plasma for reference (re-testing) purposes, if required. It is generally possible to take greater than 300 µL. Validation studies have shown that IFN-ɣ is evenly distributed in the plasma and the volume removed is not critical. The volume of plasma available can vary from patient to patient. The QuantiFERON-CMV method also allows for direct sampling of plasma from the blood collection tube using an automated system. This allows the plasma harvesting and ELISA to be performed with minimal operator input.
I want to maximise the cost effectiveness of the QuantiFERON-CMV assay by batching my samples. What is the stability associated with the harvested plasma? 2013 Harvested plasma (or plasma stored in the blood collection tubes after centrifugation) can be stored at 2°C to 8°C for up to 28 days, or below -20°C for extended periods; plasma kept at -70°C are less likely to form clots. For short-term storage (less than 28 days), it is better to refrigerate plasma samples rather than freeze them, due to possible fibrin clot formation.
What should I do if "clots" form in my plasma samples during their storage at -20What should I do if "clots" form in my plasma samples during their storage at -20°C? C? 2013 Upon thawing, frozen plasma samples may require centrifugation to sediment the clots that can form during the freeze/thaw process. A guide to dealing with clotted plasma samples is outlined in the Package Insert.
Do I need to use microtubes for storing harvested plasma? Can I use more "cost effective" ELISA plates in this instance? 2013 Uncoated ELISA plates can be used to store harvested plasma. Regardless of type, all plasma storage vessels should be sealed to avoid evaporation of samples


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