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In the present report we describe the laborious identification of the A*02010102L allele found in three healthy individuals of a French family who have shown a reduced A2 antigen expression using serological tests since the 1980s. PCR-SSP typing showed a classical A*0201 allele. Sequencing of exons 2, 3 and 4 confirmed this assignment. Sequencing of the whole gene (promoter, introns and exons 1-8) revealed one single point mutation (T to C) at position -101 in the enhancer B element region compared to the A*02010101 allele. This single mutation appears to be related to the reduced expression of the A2 antigen. This allele segregates with the haplotype Cw*12, B44, DR7, DQ2, which is different to the one described earlier.

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Thrombocytopenia occurs frequently. We will illustrate, through the presentation of a clinical case, the difficulties encountered to identify and characterize thrombocytopenia. The clinicobiological validation of a low platelet count implies, at the same time, the biologist, who must assume the validation of numeration while mentioning the morphological characteristics of the platelets and other blood cells, as well as the clinician who must interpret these data according to the clinical context. Firstly, we will detail the basic rules to correctly ensure this validation. Secondly, we will see which are the arguments which that make it possible to direct the diagnosis towards an acquired or inherited thrombocytopenia. Lastly, we will approach the classification of inherited thrombocytopenias.

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AIMS OF THE STUDY: In spite of official recommendations and measures in France, screening strategies of hepatitis C performed in the field of transfusion are not clearly known. The aim of this study is to describe the screening strategies before and after the current year of the transfusion in blood recipients in several French medical departments and hospitals. MATERIALS AND METHODS: A qualitative study using the key informant technique was carried out. A sample of 179 departments and 64 hospitals in charge of patients transfused with low or high-volumes of homologous blood products was constituted. The key informants were asked about the number of homologous blood products, the number of recipients transfused in the hospital, the volume of transfusion performed, the existence of a single defined screening strategy, the time of prescription of the biological tests (before or after transfusion), the tests performed on cryopreserved blood samples, and the indications of the transfusion. RESULTS: The main screening strategy was HCV serology (second or third generation of enzyme immunoassays) with transaminase assessments before and after transfusion in 14% of the declared screening strategies. Screening tests were more frequently prescribed after transfusion, in at least 64% of the declared screening strategies according to the volume of transfusion. HCV serology was the common test prescribed in 61 and 50% of the screening strategies for low and high-volume transfusion respectively. The screening strategies showed a large heterogeneity combining HCV serology, transaminase assessment, before or after transfusion. CONCLUSION: A great heterogeneity of screening strategies was found. The most frequent was HCV serology with transaminase assessment before and after transfusion. Recommendations on screening strategies are needed in order to limit practice heterogeneity. This study will help building a cost-efficacy model in order to guide public health decision making.

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The study reports the molecular characterization of a new DQB1 variant initially detected by unusual sequence-specific oligonucleotide (SSO) hybridization patterns in one Caucasoid individual. This new allele is identical to DQB1*0501 except for two silent nucleotide substitutions at codons 49 (GCA-->GCG) and 77 (AGG-->AGA). Compared with DQB1*0502 it differs in three nucleotides at codon 57 changing AGC (encoding Ser) to GTT (encoding Val). Considering the paternal genotype, it appears this new allele might have been generated by an interallelic sequence exchange between the two paternal DQB1 alleles.

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BACKGROUND AND OBJECTIVES: Posttransfusion hepatitis still occurs at an incidence of about 1 in 118,000 for HBV and 1 in 220,000 for HCV. This collaborative study aimed to determine the prevalence of a novel flavivirus, GBV-C/HGV, even though its role in transfusion-associated hepatitis is uncertain. MATERIALS AND METHODS: GBV-C/HGV RNA was detected by PCR using either the Boehringer detection kit or by primers previously described. HGV antibodies were detected by a serological assay from Boehringer. RESULTS: The observed GBV-C/HGV RNA frequency was 3.4%. HGV antibodies occurred in 9.5% of donors. CONCLUSION: In our study, 12. 9% of the donors had been in contact with the GBV-C/HGV virus.

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Red blood cell Agglutinates can be dissociated by providing enough energy which may be supplied by shear stress in a viscometer. In this paper a new technique is proposed to determine dissociation parameters of erythrocyte immunological agglutinates by using a laser backscattering method. Backscattered light intensity increases during the process of agglutinate dissociation when a controlled shear stress in a transparent Couette viscometer is applied. The obtained curves of dissociation can be fitted by an exponential function. A numerical integration of the dissociation curves allows us to obtain a parameter associated to the energy used in the dissociation process. A satisfactory differentiation of erythrocyte sub-groups Al, Az, A,B and Am has been carried out using this technique.

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The prevalence of HCV seropositivity observed in various populations raise the issue of the contamination routes and the corollary exclusion criteria of risk subjects from blood donation. There are various diagnostic methods for HCV infection. The biological diagnosis is reached at three levels: circulating antibody screening by second and third generation tests; screening validation by immunoblot, to distinguish between the various HCV specific antibodies and detection of viral nucleic acids by molecular biology. In blood donors in France, 0.5% were seropositive in 1990, 0.3% in 1992 and 0.1% (essentially new donors) in 1995. This decrease is the result of improved test specificity and sensitivity and donor selection. In Europe, prevalences range from 0.1-1.5% with a North-South gradient. In other countries: 0.3% in Canada, 0.6% in the USA, 1-2% in China, Thailand and Japan, from 0.2% to 20% in Africa. In risk populations contamination by blood is manifest: HCV seropositivity in 80% of drug abusers, 10-60% of dialysis patients before 1991, more than 80% of haemophiliacs treated before 1986, 10% of labile blood product recipients before 1988. The nosocomial transmission figures are even worse: 2-5% of hospitalized patients are thought to be contaminated. Perinatal and sexual contaminations are not excluded (3-30%) and they vary according to the degree of exposure and the viral type of post-transfusional HCV infection: prevention implies several types of action: information and education of populations about risk factors; medical interview before each blood donation; systematic serological testing; manufacturing measures for stable (SD processing) and labile (deleukocytation, plasma seroattenuation) blood products; prescription recommendations and follow-up measures; haemovigilance (clinical and biological follow-up of all recipients of human blood products).

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The sensitivity of the most recent generation of anti-hepatitis C virus (anti-HCV) screening tests from seven manufacturers was evaluated with a common panel of 530 specimens from 320 HCV-infected subjects. This panel included 221 samples from 57 seroconverters (53 pre-sero conversion negative specimens and 168 positive samples) and 309 selected specimens from 263 other HCV-infected patients of which 19% exhibited NS3 or core reactivity alone with the presence of HCV-RNA assessed by PCR. None of the seven screening tests detected all infectious and antibody-positive specimens. However, important differences were observed between these assays in the number of false-negative results, which seemed mainly due to nonreactivity of antibody to the NS3 antigen.

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The results concerning the hepatitis C antibodies screening tests sensitivity are presented by Viral Hepatitis Study Group of the French Society of Blood Transfusion. This evaluation was carried out in 1993, with five tests available for Hepatitis C Viral (HCV) antibodies screening. Several panels of human blood samples, collected by members of Viral Hepatitis Study Group, were used. For those specimens the data about whole serology (various reactivities against viral antigens) clinical history and other explorations (molecular biology, liver histology, other viral infections) are described. If possible all those results are used to describe some interpretation criteria for the HCV serology and sensitivity obtained for each screening test.

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Between March and November 1991, prevalence of hepatitis C antibodies was evaluated in 60,960 blood donors from the North-East of France. Using a second generation ELISA, 424 donors (0.69%) were reactive, with no significant difference between males (0.69%) and females (0.70%). Among these 424 donors, respectively 137 (32.3%), 86 (20.3%) and 201 (47.4%) were reactive, indeterminate or nonreactive by a second generation RIBA (RIBA-2) (Recombinant Immunoblot Assay). Donors with a high ELISA ratio (> or = 4) were significantly more likely to have a reactive RIBA-2. Of the 1906 donors with anti-HBc positivity (3.12%), 44 had a reactive ELISA; of these, respectively 27, 12 and 5 had a reactive, indeterminate and nonreactive RIBA. Of the 1201 donors (1.97%) with increased serum ALAT (alanine-amino-transferase) levels (> or = 2N), 42 had a positive ELISA; of these, respectively 35, 2 and 5 had a reactive, indeterminate and nonreactive RIBA. Of the 54 donors with both indirect markers, nine had a reactive ELISA; the same nine donors had a reactive RIBA. These data show that donors with both surrogate markers and a reactive ELISA are very likely to have a positive RIBA. Seventy-seven (18.16%) of the 424 donors with a reactive ELISA had at least one surrogate marker; 67 of these donors (30.04%) were among the 223 donors with a reactive ELISA and a reactive or indeterminate RIBA.

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Hepatitis C Virus, major causative agent of parenterally transmitted non-A non-B hepatitis was identified by Choo et al. in 1988 using molecular biology technologies. This virus contains a positive stranded RNA genome, it has been shown to have a small diameter. These structure and properties suggest that HCV shares many features in common with Pestiviruses and Flaviviruses. After many years of research, two major objectives were reached: -the identification of viral genome and the main purified viral polypeptide derived from recombinant yeast. Major information were recently appearing about the nucleotide sequences of different isolates coming from US, Europe and Japan; -the preparation of specific tool (ELISA anti-HCV) for detection of circulating HCV antibodies.

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