Platelets stored as concentrates are gradually activated (storage lesion), a process associated with changes in the expression of platelet procoagulant activity (PPCA). The aim of the present study was to evaluate the evolution of PPCA and the mean platelet volume (MPV) of stored platelets prepared according to the platelet-rich method (PRM) and the buffy coat method (BCM). Using the platelet factor 3 availability clotting test (PF3AT) on appropriately diluted concentrate samples, we found a decrease in PPCA expression of remnant platelets as a function of storage time (0.025 < p < 0.01 between day 1 and 7) in PRM-derived but not in BCM-derived platelet concentrates. Using the PF3AT reduction test we found a more important clotting time reduction in samples obtained from BCM than in samples obtained from PRM platelet concentrates, suggesting a higher PPCA expression of BCM platelets, not significant after 1 day but highly significant after 3 days (p < 0.0005) and after 7 days (p < 0.0005) of storage, as compared with PRM platelets. For both PRM and BCM concentrates there were no significant MPV changes as a function of storage time, but at any storage day the MPV of BCM concentrates was significantly higher (p < 0.0005) than the MPV of PRM concentrates. We conclude that the decrease of PPCA expression in PRM-derived concentrates as a function of storage time is in agreement with the gradual decrease of the platelet activation status in PRM concentrates during storage. There are probably several factors or variables causing platelets of BCM concentrates to express higher PPCA than those of PRM concentrates. Higher PPCA expression in BCM concentrates may be explained by an intrinsic platelet property, such as a difference in MPV between the two kinds of concentrates, or it may be related to an extrinsic factor such as different storage media, e.g., undiluted autologous plasma in PRM concentrates versus Plasmalyte A-diluted autologous plasma in BCM concentrates. Whether the difference in PPCA expression of remnant platelets in PRM and BCM concentrates is just an in vitro laboratory finding or may have consequences for the therapeutic efficiency of the concentrates is an interesting, still unresolved question.

Blood Coagulation↗

PubMed1999

Mutation of the repeat number of the HPRTB locus and structure of rare intermediate alleles.

During routine paternity testing a mutation of a paternal allele at the HPRTB locus was observed. The opportunity was taken to analyse this mutation at a molecular level. The repeat sequence is flanked by an imperfect repeat sequence and this region could be involved in the mutation mechanism. For this reason, we also examined the structure of "intermediate" alleles. Sequencing confirmed the insertion of a perfect repeat motif and revealed a deletion of a dinucleotide some 50 nucleotides downstream from the repeat sequence for the intermediate alleles. It is likely that these intermediate alleles are rare biallelic deletion polymorphisms and are probably not involved in the mutation or variation mechanism of this locus.

Alleles↗

PubMed1999

False-positive and false-negative results of sterility testing of stored platelet concentrates.

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Blood Preservation↗

PubMed1999

Malaria antibody ELISA insufficiently sensitive for blood donor screening.

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Animals↗

PubMed1998

Histamine synthesis by white cells during storage of platelet concentrates.

OBJECTIVES: To resolve the question whether histamine, like some cytokines, is actively synthesized during storage of platelet concentrates. METHODS: We prepared conventional buffy coat platelet concentrates and stored them in the usual way at 22 degrees C. Disodium cromoglycate was added to one series, saline to the controls. Samples were taken at intervals, to be tested for histamine and interleukin-6 (IL-6). RESULTS: The plasma histamine level increased from a median of 1.02 ng/ml (range 0.11-3.27) to 12.9 ng/ml (range 4.30-32.9) whereas the total histamine content of the platelet concentrates remained unchanged during the 5-day storage period. In contrast, the total content of IL-6 increased rapidly. CONCLUSION: Histamine is not synthesized during storage of platelets, whereas IL-6 is. The addition of disodium cromoglycate, a substance that inhibits granulocyte activation, had no effect on the release of histamine or on the total histamine content at various storage times.

Blood Platelets↗

PubMed1997

Allele frequencies of nine STR systems in the Flemish population and application in parentage testing.

In order to apply a set of nine STR loci in parentage testing, we performed a population genetic study on a sample of the Flemish population. Genotypes for HUMHPRTB, HUMFABP, HUMCD4, HUMCSF1PO, HUMTH01, HUMPLA2A, HUMPLA2A1, HUMF13A01, HUMCYAR04 and HUMLIPOL were determined using three triplex PCR reactions and silver staining. Allele frequencies showed no deviation from Hardy-Weinberg equilibrium. The frequency distribution agreed well with other Caucasian populations but three intermediate fragments, not previously found in Caucasians, were observed. We then resolved a series of 151 parentage disputes of which 103 were exclusions. In six cases, evidence for exclusion was obtained by only one informative STR locus out of eight for male children or out of nine for female children. These exclusions were confirmed with additional polymorphic markers. In one case of inclusion, a paternal allele expanded with one repeat unit of HUMHPRTB. This observation illustrates that STRs do not differ from other genetic systems in the fact that more than one excluding locus is required before exclusion is demonstrated.

Alleles↗

PubMed1997

Possible implication of sterile connecting device in contamination of pooled platelet concentrates.

Considering the possibility that a pooled random donor platelet concentrate could become contaminated by welding with a sterile connecting device, we undertook a study to determine the influence of pooling on the contamination rate. As a control group, apheresis platelets were examined. Bacteriological testing was done with a sensitive CO2 detecting culture system, the BacT/ Alert. Out of 1105 pooled platelet concentrates prepared by the buffy coat method, 15 (1.4%) were confirmed as contaminated, all with Staphylococcus epidermidis and two with a second bacterial species, i.e. Staphylococcus capitis and Propionibacterium acnes, respectively. Median detection time by the BacT/Alert was 23 h. Twelve pools of five units were contaminated, which is significantly more than the three contaminated pools of four units. On the other hand, the reuse of the welding wafers proved not be a risk factor for contamination. One welded tubing segment of a contaminated platelet concentrate failed the air leakage test, an incident which was 73 times more frequent than with the sterile platelet concentrates. We found five pooled platelet concentrates containing Staphylococci from which no bacteria could be grown from the individual buffy coats that had been pooled. We suggest the contamination here to have occurred after separation of the buffy coat from the whole blood, possibly during the welding process. Finally, none out of 378 apheresis platelet concentrates was contaminated. All our observations highlight the potential risk for contamination when making pooled platelet concentrates with a sterile connecting device. For this type of transfusion product, we advocate bacteriological screening of all units before release. The incubation time for the sterility test should, however, be limited to 36 h, if logistical problems with the availability of platelets are to be avoided.

Automation↗

PubMed1997

Higher prevalence of parvovirus B19 in Belgian as compared to Tunisian blood donors: differential implications for prevention of transfusional transmission.

Serious anaemia can be induced by human parvovirus B19 (HPV) infection in immuno-compromised patients or subjects with an haemolytic disorder. Routine inactivation procedures are insufficient to neutralize the virus, but screening for HPV is an effective means to avoid transmission by transfusion of blood components. In the present study, we have compared for the first time the IgG and IgM seroprevalence in a North African (Tunisian) and Western European (Belgian) population of blood donors. The prevalence of HPV-specific IgM was less than 2% in both populations, pointing to the absence of an epidemic. The prevalence HPV IgG was significantly (p < 0.01) higher in Belgium (74%) than in Tunisia (65%), without any relationship with age or sex. This finding may suggest a south-north gradient of this infectious disease. Since the presence or absence of HPV-specific antibodies does not preclude transfusional transmission, screening for the virus itself should be done to avoid iatrogenic infection in HPV-naive subjects at risk. In view of the different transfusion policies in Belgium and Tunisia, a strategy for each of both countries is proposed.

Adolescent↗

PubMed1997

Prevalence of hepatitis A, B and C in the Flemish population.

Viral hepatitis is a serious health problem throughout the world. No recent prevalence data on hepatitis A, B and C were available for the population in Flanders, Belgium. For this reason, a sero-epidemiological study was undertaken in 1993-1994 in a sample of the general population. The purpose of this study was to obtain a clear picture of the prevalence of hepatitis A, B and C. Between April 1993 and February 1994, 4,058 blood samples were drawn and collected in 10 hospitals in Flanders. The study group was representative for the Flemish population. For hepatitis A a seroprevalence of 55.1% was found. In the non-Belgian residents the HAV prevalence was significantly higher than in Belgians (62% versus 52%; chi2 = 8.05; p = 0.005). For hepatitis B. 9.9% of the study group showed serological evidence of hepatitis B markers: 6.9% of the participants was positive for anti-HBs/anti-HBc, 0.7% appeared to be HBsAg positive and 3.5% was solely anti-HBs positive. The prevalence of HBV markers in Belgians was 6.9%, significantly lower compared to the 13.4% among non-Belgians (chi 2 = 14.05; p = 0.00018). 4055 serum samples were analysed for hepatitis C serology by second generation anti-HCV tests. Anti-HCV was detected in 0.87% of the serum samples. No statistically significant difference was found in HCV prevalnece between Belgians and non-Belgians. Results of this study should help policy makers in their decisions on the most appropriate hepatitis A and B vaccination strategy and on the most effective prevention strategy for hepatitis C.

Adolescent↗

PubMed1997

A multicenter evaluation of the routine use of a new white cell-reduction apheresis system for collection of platelets.

BACKGROUND: Residual white cells (WBCs) cause serious side effects in platelet transfusion. An in-line WBC-reduction system based on fluidized particle bed technology was recently developed as a modification of an existing plateletpheresis system. STUDY DESIGN AND METHODS: In an investigational phase, three flow profiles were evaluated using prototype software in five centers, each using their standard conditions. In the confirmatory phase, the released software was tested in three centers. WBCs were counted in two full Nageotte grids (dilution 1-in-5). RESULTS: With the prototype software, WBC levels were always below 1 x 10(6) per procedure (median, 25,000/procedure; n = 314). One profile proved to be superior to the other two with respect to platelet yield and residual WBCs, and it was incorporated in the released WBC-reduction system, together with a built-in process control. Median residual WBCs in these WBC-reduction system components not rejected by the process control were 19,000 per procedure (n = 211/225 total), with 99.5 percent of the platelet components having less than 1 x 10(6) WBCs. CONCLUSION: The protocol selected in the initial phase, now available as a WBC-reduction system, results in platelet concentrates with very low residual WBC levels. This satisfies even the most stringent criteria for WBC reduction in platelets, without the platelet loss typically seen with conventional fiber filtration.

Blood Platelets↗

PubMed1997

Loss of D and C expression in chronic myelomonocytic leukemia.

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Aged↗

PubMed1996

Febrile reactions to platelet transfusion: the effect of increased interleukin 6 levels in concentrates prepared by the platelet-rich plasma method.

BACKGROUND: A relation between febrile reactions to platelet transfusion and high cytokine levels in platelet concentrates (PCs) was found previously. The levels of cytokines such as interleukin (IL)-6 are related to the while cell content of the PC during storage. Therefore, early removal of white cells should prevent reactions. STUDY DESIGN AND METHODS: This prospective study was set up to compare methods for the preparation of random PCs, the platelet-rich plasma method (PRP-PCs), which results in a high white cell content, and the buffy coat method (BC-PCs), which results in a low white cell content, with regard to the frequency and severity of reactions to platelet transfusion and the IL-6 level of the PC. IL-6 was chosen because it is the major mediator of the acute-phase response. White cells were reduced in all PCs before transfusion. RESULTS: Platelet transfusions (n = 584) in 64 patients were studied. An overall reaction frequency of 7.2 percent was observed. Transfusion reactions were seen predominantly in patients who received PRP-PCs (PRP-PCs: 9.3% vs. BC-PCs: 2.7%, p = 0.007). Allergic reactions were limited to transfusions of PRP-PCs. The following PRP-PC characteristics were significantly correlated with febrile transfusion reactions: IL-6 level (p < 0.0001), initial white cell count (p = 0.001), and storage time (p = 0.02). In this group, reactions were less frequent in patients receiving pretransfusion medication (p < 0.001). In the PRP-PC group, IL-6 content (p = 0.01) and initial white cell count (p = 0.04) were also significantly correlated with allergic reactions, which indicated that these or associated factors might have an effect on the outcome of this type of reaction. CONCLUSION: Febrile reactions are highly correlated with IL-6 levels in PCs. The low white cell content of BC-PCs is associated with undetectable IL-6 levels and a reduced frequency of febrile as well as allergic reactions in recipients. The BC method is the preferable one for the production of random-donor PCs.

Acute-Phase Reaction↗

PubMed1996

Efficient and safe definition of the rhesus-negative donor on the olympus PK 7200 without the indirect antiglobulin test for weak D.

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Blood Donors↗

PubMed1995

The role of cytokines in blood transfusion reactions.

Recent advance in the understanding of the mechanism of hemolytic transfusion reactions results from the investigation of cytokine generation in in vitro models of incompatible red blood cell transfusion. Cytokines with pyrogenic and pro-inflammatory activities as well as cytokines with activating properties for granulocytes, monocytes and endothelial cells are produced in both 'intravascular' and 'extravascular' types of hemolytic reactions. It has also been demonstrated that cytokines are generated and accumulated in blood components such as platelet concentrates, during storage. A large part of febrile transfusion reactions results from transfusion of stored platelet concentrates containing high cytokine levels and not from antigen-antibody reactions. Prestorage removal of white blood cells, which generate cytokines during storage, from platelet concentrates reduces strongly the reaction incidence and should be standard practice.

Blood Transfusion↗