[Platelet-leukocyte aggregates as a marker for platelet activation in platelet concentrates]. / Complexes leucoplaquettaires en tant que marqueur d'activation dans les concentrés plaquettaires standards.

OBJECTIVES: Several in vitro laboratory tests to assess the quality control of platelet concentrates (PC) are available. Some of them have a good correlation with the platelet recovery index. To assess the quality control of standard PC prepared in our blood bank, we measured the blood gas and the degree of platelet activation. MATERIALS AND METHODS: SPC were prepared by the PRP method. Fifty-five SPC (45 SPC at day one of storage and 20 SPC at day five of storage) were analysed. Blood gas (pH, PO(2), PCO(2) and bicarbonate concentration) in the SPC were measured by blood gas automate. Platelet activation profile were determined by measuring the percentage of platelet expressing the CD62p (% CD62) and the percentage of platelet-leukocyte aggregate (% PLA). RESULTS: The pH values of all studied SPC were comprised between 7.0 and 7.6. SPC at day 1 of storage have a significantly higher pH than those at day 5 of storage (7.5+/-0.05 versus 7.3+/-0.14; p<0.001). The % CD62p were higher in SPC at day five compared to the SCP at day one without reaching a statistical significance (28.4+/-15% versus 24.3+/-9.7%, p=0.052). The percentage of PLA were higher in SPC at day one compared to SCP at day five although this difference is not statistically significant (22.2+/-7.5% versus 17.9+/-8.0%; p=0.23). CONCLUSION: Preparation and storage procedure adopted in our centre did not significantly affect the quality SPC. Our study is the first to assess the PLA in PC. Studies assessing the PLA are warranted to appreciate the clinical impact of this parameter.

Treatment of haemophilia A in Tunisia: efficacy and inhibitor study.

Cryoprecipitate is the principal type of factor VIII (FVIII) concentrate used for treating haemophilia A in Tunisia. Allergic reactions, viral transmission, and inhibitor formation remain the most serious complications of FVIII therapy. The aims of the study presented here were to evaluate the efficacy of FVIII therapy, to investigate the inhibitor prevalence, and the factors which may affect inhibitor formation in our haemophilia A patients. Plasma samples were screened for FVIII inhibitors by the Bethesda method. 30 minutes FVIII recovery was also determined for each patient. In this prospective study, 18 previously treated haemophilia A patients, four with severe (FVIII concentration <2%) and 14 with moderate haemophilia, were closely followed up during administration of 223 FVIII concentrates (cryoprecipitate and/or fresh frozen plasma). The median age of the patients involved in the study was 13.5 years (range 5 to 53). Clinical response to FVIII was consistently good to excellent. In the majority of cases, actual and predicted FVIII recovery correlated' well. Adverse reactions were not observed. Five patients, aged less than 18 years and minimally treated (>36 FVIII exposure days), were found to have low titre FVIII inhibitors (<10 Bethesda units) at the end of the study. Inhibitor activity was detected in one patient with severe and in four patients with moderate haemophilia. In conclusion, FVIII therapy was effective, well tolerated, and low titre inhibitors identified did not preclude continued on demand FVIII therapy. Our study has also demonstrated that patients' age and treatment regimen do not affect inhibitor formation. Further studies are necessary to confirm these findings.

[Quality control of platelet concentrates: experience of Sousse (Tunisia) blood centre]. / Contrôle de qualité des concentrés plaquettaires: expérience du centre de transfusion de Sousse (Tunisie).

The aim of this prospective study was to control the quality of platelet concentrates prepared in Sousse blood centre: standard platelet concentrates (SPC) and apheresis platelet concentrates (APC) in order to detect anomalies and apply corrections. The quality control included three parameters: pH, volume, cells count: platelets, residual white blood cells (WBC) and red blood cells (RBC). The SPC pH was measured with pH meter, samples were obtained at the end of shelf-life by the destructive method. The control of SPC cells count was determined with a Beckman coulter, samples were collected by the stripping method. The APC quality control was assessed in the same conditions than those described for SPC but samples were collected by the transfer method. Quality control results were compared to Europe standards. During a period of six months (July-December 2002), 475 SPC (16% of the production) and 36 APC (60% of the production) were controlled. More than 95% of the SPC meet standards in regard to pH, volume and residual WBC count. However, the number of platelets and residual RBC meet standards respectively in 58% and 42% of SPC. All the APC meet standards for the three quality parameters. In conclusion, in order to improve the quality of our SPC, in regard to the number of platelets and residual RBC, two actions are respectively necessary to satisfy requirements: collecting the appropriate volume of whole blood and controlling the separation technique.

[The utility of class I HLA antibodies screening in a Tunisian obstetric department in order to select good HLA typing reagents]. / Intérêt du dépistage des anticorps anti-HLA de classe I dans un service obstétrical tunisien pour la sélection de bons réactifs de typage HLA.

In order to reduce the cost of the serologic class I HLA typing, we have established a screening program for HLA antibodies among obstetric patients. Class I HLA antibodies were identified by standard microlymphocytotoxicity test using a panel of 100 lymphocytes. In the study period, carried out between January 2000 and June 2002, 817 women were tested, most of them (62%) during the last trimester of pregnancy and in the other cases after delivery. These patients, aged between 18 and 45 years, were in the majority (88%) multiparous. From the total number of 817 maternal serum samples screened, 194 specimens (23,74%) tested positive for HLA antibodies. Thirty eight HLA specificities were characterised in 110 maternal sera of which 62 contained monospecific HLA antibodies. HLA-A2 and HLA-B51(5) were the most common specificities characterised in this study. HLA alloimmunization was present since the first pregnancy. There was no statistically significant linear correlation between HLA alloimmunization and the number of pregnancies. Fifty maternal serum samples (6,11%) could be used as HLA typing reagents. Of these 50 sera, 36 had monospecific HLA antibodies. These useful antisera covered a total of 30 specificities: 8 HLA-A and 22 HLA-B. The cost of self - screening for useful antisera as estimated at dollars 62/mL, the personnel was not considered. However, the lowest cost of commercial HLA typing sera is approximately dollars 400/mL. Our study showed the utility and the net economic advantage to use maternal sera as reagents in our new HLA laboratory with limited budget.

[Role of ALAT level in preventing post-transfusional hepatitis. Prospective study of 1,180 blood donors in Tunisia]. / Intérêt du dosage de l'ALAT dans la prévention des hépatites post transfusionnelles. Etude prospective à propos de 1180 donneurs de sang du sahel tunisien.

In Tunisia, regular serological tests for prevention of blood transmitted hepatitis consist in the research of HBS antigen and HCV antibodies. Our purpose in this study is to estimate the prevalence of hypertransaminasemia in blood-donors and to determinate to what extent it could prevent blood-transmitted hepatitis. Therefore we have assessed ALAT sera level in 1180 blood-donors. It rate is considered elevated if higher than twofold the normal rate (> N = 40 Ul/l). Donors with high ALAT level were summoned three months later after their blood gift to undergo clinical examination and a new serological test, researching seroconversion of HBS Ag and HCV antibodies. With regarding to estimation of residuel HCV infection risk, we were based on M.P Busch's data. Hpertransaminasemia was modified in 134 individuals (11.5%). Only 67 had replied to our summons. Alcoholism was involved in one case. Smoking was found in most of male donors. We had discovered neither weight excess nor drug or medicines consumption which could explain increasing ALAT. New serological list had revealed seroconversion for HCV antibodies in ELISA but with undeterminated profile in Immunoblot (anti NS5 solely). PCR was not carried out. Residual infection risk being considered, use of hypertransaminasemia detection in blood donors should prevent nearly 1.67 blood transmitted hepatitis per million transfusions units. However if we consider shortage in blood derivates in Tunisia, such a decision should be comprehensively weighted numerous blood donors will be moved aside.