[Identification of alloantibodies and their associations: balance sheet of a year at the Auvergne-Loire French Blood Establishment]. / Identification d'allo-anticorps et leurs associations : bilan d'une année à l'Établissement français du sang Auvergne-Loire.

OBJECTIVES: Some alloantibodies and their combinations can lead to delays or even an impasse in a transfusion, owing to the necessity of finding compatible red blood cell concentrates. The aim of this study was to determine the specificities of the most common alloantibodies, as well as the most common combinations of alloantibodies. METHODS AND MATERIALS: A retrospective study analysed erythrocyte alloantibodies identified in 2008 in the immunohematology laboratories at the Auvergne-Loire French Blood Establishment. The following data were studied: frequency, specificities of the alloantibodies, date of discovery, and patient age and sex. RESULTS: One thousand eight hundred and fifteen alloantibodies were identified in 1575 patients (median age: 63.5years, female/male ratio: 3.03). The most common alloantibodies were directed against the following antigens: RH3/E (18.7%), KEL1/K (17.3%), RH1/D (16.4%), MNS1/M (9.4%), FY1/Fya (6.9%), RH2/C (6.1%), KEL3/Kpa (4.7%), JK1/Jka (4.3%) and RH4/c (4.1%). In 13.1% of patients, at least two alloantibodies were identified. The pairs most frequently combined were anti-RH1/RH2, anti-RH3/RH4 and anti-RH3/KEL1. CONCLUSION: Specific associations of paired alloantibodies were identified. The main combinations provide indications on the choice of red cell concentrates in the inventory for a given patient. The data collected in our study show that when an antibody is identified, it is recommended for subsequent transfusion episodes to respect the phenotype RH 1-5 (D, C, E, c, e) and KEL1 (K) of the patient, and if possible antigens JK1 (Jka) and FY1 (Fya), and to a lesser extent MNS3 (S). Detailed knowledge of the immunological mechanisms leading to the formation of these alloantibodies and their combinations would allow better prevention of erythrocyte alloimmunization.

[Guidelines for medical prescription of medical laboratory tests]. / Recommandations concernant la prescription d'examens de biologie médicale.

The implementation of a computer-assisted prescription is interesting for the laboratory to achieve requirements of NF EN ISO 15189 standard. The test redundancies are also studied and guidelines, founded on validated studies, are proposed. Some solutions concerning the management of orally-formulated prescriptions are given. Finally, a model of collaboration contract between the medical laboratory and the clinical unit is proposed.

[Management of pre-analytical nonconformities]. / Outils pour la gestion et la maîtrise des non-conformités pré-analytiques.

The main nonconformities enumerated to facilitate consensual codification. In each case, an action is defined: refusal to realize the examination with request of a new sample, request of information or correction, results cancellation, nurse or physician information. A traceability of the curative, corrective and preventive actions is needed. Then, methodology and indicators are proposed to assess nonconformity and to follow the quality improvements. The laboratory information system can be used instead of dedicated software. Tools for the follow-up of nonconformities scores are proposed. Finally, we propose an organization and some tools allowing the management and control of the nonconformities occurring during the pre-examination phase.

[Anti-RH1 (anti-D) alloimmunization after transfusion of platelet concentrates from RH :1 donors]. / Allo-immunisation anti-RH1 (anti-D) après transfusion de concentrés plaquettaires issus de donneurs RH :1.

Anti-erythrocyte alloimmunization may occur following the transfusion of platelet concentrates, in response to the presence of residual erythrocytes. Immunization against RH1 (D) antigen is the most frequent, but transfusion of RH1 compatible platelet concentrates is not always possible because of supply constraints. We report here three cases of anti-RH1 (anti-D) alloimmunization in RH :-1 patients after transfusion of platelet concentrates from RH :1 donors. Criteria for selection of platelet concentrates are numerous and difficult to achieve in practice. Respect of RH1 compatibility is not obligatory, but in case of transfusion of RH1 incompatible platelet concentrates, anti-RH1 immunoprophylaxis must be made for RH :-1 women of child-bearing age and without profound immunosuppression, as recommended by Afssaps (Agence française de sécurité sanitaire des produits de santé). These data point out the need to perform post-transfusional screening test for irregular erythrocyte antibodies as part of the transfusion of platelet concentrates.

[Identitovigilance and its impact on the results ensuring the transfusion security]. / Identitovigilance et son impact sur les résultats d'immuno-hématologie érythrocytaire assurant la sécurité transfusionnelle.

Errors on identity of patients during their registration may lead to non-compliance with a transfusion procedure, a non-issue adjusted blood and thus a transfusion risk. The main mistake is the misknowledge of an antibody, secondarily a loss of transfusion information and a redundancy of examinations. The creation of a working group "identitovigilance" helped sensitize the staff of health establishments and clinical chemistry laboratories. In this area of computerization of medical and transfusion records, shared folders and networking, identification of patients is a real issue of risk management hospital.

[Redox status in HIV+ patients under HAART]. / Statut oxydatif de patients VIH positifs sous trithérapie.

Oxidative stress decreases immune defences and is also suggested to participate in the activation of HIV virus replication. That is why we decided to explore some biomarkers of oxidative stress (reduced glutathione, lipoperoxides, true malondialdehyde and vitamin C) in 20 HIV positive patients whose HIV replication was determined by measurement of RNA viral load. Reduced glutathione is decreased in HIV positive patients, without correlation with the viral load. The patients mean content of lipoperoxides is twice that of controls but with such a large range that there is no statistical difference.

[Plasma ascorbic acid: preanalytical factors and new HPLC method]. / Acide ascorbique plasmatique: facteurs préanalytiques et nouvelle méthode de mesure.

We describe a fast ED-HPLC method for ascorbic acid analysis, carried out on a new mixed mode chromatographic column. Due to its functional dodecylsilane group associating a quaternary ammonium, this column is simpler and easier to handle than previous ones because without any counter-ion in the mobile phase. As ascorbic acid and glutathione are very often measured on the same blood sample, it was efficient to validate a common pretreatment solution for ascorbic acid in plasma and glutathione in whole blood. This pretreatment is based on the use of a sulfosalycilic acid, N-ethylmaleimide, EDTA mix recently described. Plasma samples, stored after deproteinisation and without centrifugation, are stable for three weeks at -20 or -80 degrees C.

Apolipoprotein(a) size polymorphism in young adults with ischemic stroke.

High serum lipoprotein(a) (Lp(a)) concentration which is largely determined by genetic factors, mainly the apolipoprotein(a) (apo(a)) polymorphism, is associated with ischemic cerebrovascular disease. The aim of this study was to investigate whether apo(a) size was associated with acute ischemic stroke in young adults for which causal factors often remain undetermined. Lipid parameters, Lp(a) concentration and apo(a) isoform size distribution were determined in 90 young patients (37.4+/-8.7 years) with acute cerebral ischemia, and compared to those of control subjects with similar age and sex ratio. Apo(a) size was expressed as its apparent number of kringle 4 (Kr 4) repeats. Serum Lp(a) concentrations were significantly higher in patients than in controls (median values: 0.18 vs. 0.07 g/l, P=0.009) and were as expected inversely related to the number of kringle 4 repeats in both controls (r2=-0.61, P < 0.001) and patients (r2=-0.56, P < 0.001). However there was no difference in the apo(a) isoform size distributions between the two groups (median isoform size: 27 vs. 27 Kr 4, P=0.25). Lp(a) levels were increased as well in patients with size apo(a) isoform < or = 22 Kr 4 as in those with isoforms > 25 Kr 4. Multivariate analysis showed that apo(a) phenotype did not appear as a risk factor for cerebrovascular infarction. Thus, our results indicate that serum Lp(a) was significantly increased in young people with ischemic stroke but fail to reveal a role of small-sized apo(a) isoforms in the occurrence of this event. They suggest that other factors, genetic or environmental in nature, than the apo(a) size contribute to increase the serum Lp(a) concentrations in these young patients.

Enhanced susceptibility of low-density lipoprotein to in vitro oxidation in type 1 and type 2 diabetic patients.

Macrovascular disease represents a major cause of morbidity and mortality in patients with diabetes mellitus. Low-density lipoprotein (LDL) is involved in the pathogenesis of atherosclerotic lesions, through modifying processes such as oxidation. We examined the in vitro susceptibility to oxidation and the oxidizability of LDL isolated from the plasma of Type 1 and Type 2 diabetic patients. Two groups of diabetic patients (20 Type 1, 20 Type 2) were compared with sex- and age-matched non-diabetic control groups. In vitro oxidation of the purified LDL preparations was assessed by determination of the kinetics for the formation of conjugated dienes (lag phase duration, maximal rate and maximal dienes concentration) and by measurement of thiobarbituric acid-reacting substances (TBARS) in the presence of copper ions. LDL from both Type 1 and Type 2 diabetic patients exhibited a shorter lag phase duration for conjugated dienes formation (94 +/- 14 vs. 108 +/- 20 and 97 +/- 26 vs. 112 +/- 18 min for Type 1 and Type 2 diabetic groups vs. respective control groups, P < 0.05). We also observed an increase in maximal rate of conjugated dienes formation (2.21 +/- 0.55 vs. 1.52 +/- 0.31 and 2.02 +/- 0.55 vs. 1.52 +/- 0.31 nmol/mg LDL/min, P < 0.01) and of maximal production of TBARS (77.9 +/- 11.8 vs. 65.5 +/- 10.4 and 76.7 +/- 9.9 vs. 65.3 +/- 9.4 nmol/mg LDL protein, P < 0.05) in diabetic groups. Our results demonstrate both a higher susceptibility to oxidation and a higher oxidizability of LDL from diabetic patients, as much for Type 1 as Type 2 diabetic subjects with or without pre-existent vascular complications. This enhanced propensity of LDL oxidation in patients with diabetes mellitus could at least partly be attributable to quantitative and qualitative alterations in the chemical composition of LDL and to the glycoxidation process occurring on these lipoproteins.

Discrepancies between lipoprotein(a) concentrations in icteric sera measured by immunonephelometry and electroimmunodiffusion.

We compared the lipoprotein(a) [Lp(a)] levels in 32 icteric sera determined both by an electroimmunodiffusion assay (EIA), using the Hydragel Lp(a) kit (Sebia, France) and by two immunonephelometric assays, one on a Behring Nephelometer Analyzer (BNA), using antiserum from immunofrance, and the other on a Beckman analyzer (Array), using antiserum from Dako (Denmark). With the EIA assay, the Lp(a) level was 0.09 +/- 0.09 (mean +/- SD in g/L), with the BNA assay, 1.01 +/- 1.51 and with the Array assay, 0.05 +/- 0.05. Sample blanks values (0.76 +/- 1.28 g/L) demonstrated that the high Lp(a) levels obtained in the BNA assay are caused by nonspecific precipitation. Analysis of the precipitate indicated the presence of Lipoprotein X, an abnormal lipoprotein that appears in the serum of patients with obstructive jaundice or with lecithin-cholesterol acyltransferase deficiency. The precipitant seems to be polyethyleneglycol (PEG) that was added to the reaction medium in both the BNA and the Array assays to stabilize the Lp(a)-anti Lp(a) immune complex. In the Array assay, interference by this nonspecific precipitation is eliminated by preliminary centrifugation of the diluted sample. However, coprecipitation of Lp(a) could occur during this step. Consequently, the results of Lp(a) measurement in serum from patients with hepatobiliary diseases should be interpreted with caution when immunonephelometric assays are used with a medium containing PEG.

Serum LpAI lipoprotein particles in diabetic patients with and without renal lesions of different grades.

Among high density lipoprotein particles, LpAI particles which contain apolipoprotein A1 alone, appear to be involved in cholesterol transport from peripheral tissues to the liver. The aim of this cross-sectional study was to examine serum LpAI particle concentrations in Type 1 and Type 2 diabetic patients with renal lesions of differing grades, in comparison with normal controls and with nondiabetic patients presenting with chronic renal failure. LpAI concentrations and LpAI-to-apo A1 ratios were increased in Type 1 diabetic patients with normal albumin excretion. In Type 1 and in Type 2 diabetic patients with increased urinary albumin excretion, LpAI concentrations and LpAI-to-apo A1 ratios were found to be not different from those of normal controls. In diabetic and in nondiabetic patients with chronic renal failure, LpAI concentrations were decreased. These abnormalities may contribute to the development of macrovascular complications.