Transmissible spongiform encephalopathies (TSEs) have been recognised around the world for many years. Creutzfeldt-Jakob disease (CJD), one of the human forms of TSE, has been studied widely and thus far has not proved a great threat to human health. The emergence of two new TSEs--bovine spongiform encephalopathy (BSE) in cattle and variant Creutzfeldt-Jakob disease (vCJD) in humans in the UK--has caused great concern. BSE has had an economic impact and vCJD is a threat to human health. It has been shown that these two diseases are caused by the same prion agent and are linked. Research indicates that vCJD behaves differently to CJD and there is strong evidence to suggest that vCJD is present in lymphoid tissues and B lymphocytes, which presents a theoretical risk that it may be transmitted by transfusion of blood and blood products. To minimise/prevent this risk, the UK government has decided that plasma should be sourced from abroad and has instructed the National Blood Service to leucodeplete all blood and blood products, at a cost of 70 million pounds per annum, although it is not known if this will remove this risk.
"The measure was predicated on studies suggesting that B lymphocytes were likely to be involved in the initial phases of disease and that leucocytes were an important locus of infectivity in the peripheral blood. Subsequently, it has become apparent that in animal studies leucodepletion does not reduce infectivity in plasma and is likely to reduce the prion concentration in blood by only about 40% (Prowse & Bailey, 2000; Gregori et al, 2004; St Romaine et al, 2004). Universal leucodepletion is also considered to offer a number of additional benefits, e.g. "
[Show abstract][Hide abstract] ABSTRACT: Whereas plasma-derived clotting factor concentrates now have a very good safety record for not being infectious for lipid enveloped viruses, concern has arisen about the possibility that prion diseases might be transmitted by blood products. There is epidemiological evidence that classical sporadic Creutzfeld Jakob disease (CJD) is not transmitted by blood transfusion. There is now good evidence that the abnormal prion associated with variant CJD can be transmitted by transfusion of fresh blood components and infect recipients. To reduce the risk of the pathological prion in the UK infecting recipients of clotting factor concentrates, these are now only manufactured from imported plasma collected from countries where there has not been bovine spongiform encephalopathy (BSE) in cattle and the risk of variant CJD in the population is, therefore, considered negligible. The safety of these concentrates is also enhanced because prion protein is, to an appreciable extent, excluded by the manufacturing process from the final product. To help reduce the chance of prion transmission by fresh blood products, donations are leucodepleted, there is increasing use of imported fresh frozen plasma (especially for treating children) and potential donors, who have been recipients of blood since 1980 (the beginning of the BSE epidemic in cattle) are deferred.
British Journal of Haematology 02/2006; 132(1):13-24. DOI:10.1111/j.1365-2141.2005.05796.x · 4.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: There is no doubt that the introduction of quality system principles and regulation to blood and tissue services in the 1990's has brought about significant improvements in the control of processes and the quality of products being released for patient care. But, as regulation extends into new areas of cellular and tissue therapy, it is perhaps time to review the regulatory paradigm within which we work, and the principles that underpin it. At what point do the costs of regulation exceed the benefits to be gained? At what point to regulations cease to yield measurable benefits to patient care and safety at all, but instead become simply a burden on service providers and businesses, and ultimately the community as a whole? And is there a point at which regulation actually compromises patient care and safety, or the development of new technologies? In the early stages of regulation, there is demonstrable cost-benefit as assessed by product quality and patient outcomes. However, there is inevitably a "law of diminishing returns", whereby the degree of improvement that can be achieved decreases and the cost of achieving that benefit increases. What has not yet been determined is whether, as regulations and regulators become more precise and more demanding, there remains a measurable net cost benefit over time, or whether there is a point at which the cost of further improvement matches, or even exceeds, the benefits to be gained. A key underpinning of the regulatory philosophy is the "Precautionary Principle". This paper will focus on the application of the Precautionary Principle in the area of blood and tissues, which encompasses the burgeoning field of cellular therapies.
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