NR AAYU
AU Barbara,J.A.J.
TI Prions and blood transfusion
QU Transfusion Science 2000 Feb-Apr; 22(1-2): 49
PT journal article
VT With the advent of the human form of BSE - new variant CJD (vCJD) - the question of prion transmission by blood transfusion had to be reexamined. To date there is no epidemiological or 'look-back' evidence that CJD is transmitted by blood transfusion. However, absence of evidence of risk is not necessarily evidence of absence of risk. Experimentally, prions can be demonstrated in the blood of infected animals, but only when infected blood is inoculated directly into the brains of other animals. This indicates that the amount of prion in the blood is very low. But several questions arise when we consider vCJD. Is the amount of vCJD higher in blood compared with classical CJD? We know that vCJD has a greater association with lymphoid tissue as it has been found in tonsils and the appendix of infected humans (and this forms the basis for preliminary population screening). A subgroup of white cells, the B lymphocytes, have been shown to be a pre-requisite for infecting nervous tissue in the body, hence the decision to remove white cells from all blood components, i.e., leucodepletion. How many potential donors are infected with vCJD? Classical CJD appears in only 1 person per million per annum. Up to the end of 1998, 35 cases of vCJD had been reported and potentially more people could be infected but as yet, we do not know how many people are infected. Interestingly all the cases show methionine homozygosity in codon 129 of the infected individual's prion protein, suggesting increased susceptibility to vCJD in 37% of the population who have this genetic constitution. Whether or not vCJD proves to be transmissible by transfusion will be influenced by the various factors discussed above. In the meantime, 3 of the 35 people who have developed vCJD have been blood donors, resulting in two enormously disruptive worldwide recalls of British prepared fractionated blood products. Hence the government's decision to 'err on the side of caution' and make fractionated blood products like clotting factors, albumin and anti-D immunoglobulin from plasma collected in countries where there have been no clusters of vCJD reported. As a result, in England plasma is being imported from North America for the manufacture of products.
MH Blood Component Removal; Blood Transfusion/*adverse effects/standards; Creutzfeldt-Jakob Syndrome/blood/genetics/transmission; Human; Leukocytes/chemistry/pathology; PrPsc Proteins/*blood
AD John Barbara, National Blood Service, North London, Colindale Avenue, London NW9 5BG, UK
SP englisch
PO England