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and NRA. Further complementary guidance with respect to the production of plasma for fractionation is available in WHO recommendations for the
production, control and regulation of human plasma for fractionation 3.
9.4.3.5 Cryoprecipitate and Cryo-poor plasma
Cryoprecipitate is the cryoglobulin fraction of plasma and contains a major portion of the Factor VIII, von Willebrand factor, fi brinogen, Factor XIII
and fi bronectin present in plasma. Cryoprecipitate is obtained from fresh frozen plasma that is prepared in a way that protects Factor VIII stability.
Plasma is allowed to thaw either overnight at 2–6°C or by a rapid-thaw technique. Following thawing, the supernatant cryo-poor plasma and the
cryoprecipitate are separated by hard-spin centrifugation. The cryo-poor plasma is then expressed into a transfer bag. The two components are
refrozen to the appropriate core temperature.
Stability during storage depends on the storage temperature. Storage temperature and shelf-life depend on the intended use of the product. For
long-term storage for two years or longer the optimal storage temperature is minus 25°C or colder.
Periodic quality control should be performed on the fi nal product to ensure that the manufacturing process is consistent see 9.6. At a minimum, the
following critical parameters should be checked during the quality control assays of cryoprecipitate:
— volume; — Factor VIII activity;
— clottable fi brinogen; — von Willebrand factor activity if applicable.
Virus inactivation andor quarantine are applied in some countries. Under certain circumstances the use of small pool preparations of
cryoprecipitate by pooling single-donor cryoprecipitate units may be desired.
9.5
Laboratory testing
9.5.1
Screening tests for infectious disease markers
9.5.1.1 Testing requirements
The following tests, which are considered mandatory by all regulatory agencies, are relevant to the preparation of blood components and should
be performed on each individual blood donation:
— an approved test for Hepatitis B surface antigen HBsAg; — an approved test for anti-HIV1HIV2;
— an approved test for anti-HCV.
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All three tests have to be negative. Initially reactive donations should be retested in duplicate by the same assay. Products from a repeatedly reactive
donation should not be used for therapeutic applications and should normally be destroyed unless useful for non-therapeutic purposes or investigations.
A sample of the donation should be evaluated by a confi rmatory test. There should be a system for notifying and counselling the donor if confi rmation
is positive. It is recommended that national algorithms should be developed and used to enable consistent resolution of discordantindeterminate or
unconfi rmed results.
In some countries, additional serological testing is required — for instance, anti-HBc testing may be performed on whole blood donations in order to
further reduce the risk of exposure of recipients to HBV by contaminated blood or blood components 3. Additional testing for other agents or markers — such
as anti-HTLV III, anti-T.cruzi or West Nile Virus WNV — may be required by the NRA, taking into account the epidemiological situation in any given
region or country or the frequency of donating blood. In addition to testing for immunochemical-serological infectious disease markers, NAT testing of
blood donations for the virus genomes has been introduced in some countries to increase the chance of identifying infected donors.
During the natural course of infection, viraemia usually occurs signifi cantly at a point earlier than that at which immunochemical markers antibodies
can be detected in the infected serum. Thus, infection may be detected by NAT up to 50–60 days before seroconversion i.e. to HCV occurs. Testing
for the presence of nucleic acid may be performed for viruses such as HCV, HBV, HIV, HAV, WNV where appropriate andor Parvovirus B19, and
the application of this technology may be extended to other transmissible microbes. NATs require a particularly sophisticated laboratory environment,
special equipment and specially trained laboratory personnel. Mainly because of an extraordinary risk of false-positive results due to the so-called
“carry-over” inadvertent transfer of the amplifi cation product DNA to neat donor samples, very stringent handling and logistics are mandatory.
In contrast to testing for the serological markers of individual donor specimens, NAT testing may be performed following current practices
by assembling various samples in mini-pools. However, this requires a thoroughly validated system of sample labellingidentifi cation, a validated
strategy and pooling process, and a validated algorithm to resolve pool results to individual donors. Hence, a specifi c logistics system may have to
be established not only in the laboratory but also at the blood establishment in order to collect and suitably label samples. Contiguously tracing samples
through the whole process from the donor, through pooling if applicable, testing and release of the donation may present a particularly demanding
challenge.
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A system should exist in the country or region for approval of test systems, such as an offi cial approval system by the NRA or a delegated laboratory.
The required minimal sensitivity of tests for the different antigensantibodies or nucleic acids should be defi ned by the NRA.
9.5.1.2 Handling of samples and data
