The use of mean platelet volume for evaluation of quality of platelet concentrates.

Mean platelet volume (MPV) was determined on whole blood and platelet concentrates (PC) prepared from units of the same blood, as well as on samples of venous blood taken from donors before plateletpheresis and on PC collected by Spectra (COBE Laboratories Ltd) and CS-3000 (Baxter Healthcare Ltd) cell separators. The mean (+/- SD) MPV for PC prepared from blood (7.18 +/- 0.

An overview of current trends in platelet preparation, storage and transfusion.

We present an overview of issues relating to preparation, storage and transfusion of platelet concentrates. The concepts of quality are described and potential benefits from leucodepletion, UVB irradiation and the use of additive solutions discussed. Emphasis is placed on laboratory evaluation of the storage lesion and in particular morphological changes of platelets during storage.

[The need for national transfusion services].

Continuing advances in medical and surgical treatment have resulted in increasing demands for blood and blood derivatives. In most developed countries and in many developing ones, the blood transfusion services are organised centrally either as National Blood Transfusion Services or under the auspices of organisations such as the League of Red Cross or Red Crescent Societies. Centrally organised services have been shown clearly to be superior to hospital based transfusion services.

Anti-HBs detection: a modified passive haemagglutination assay.

Modification of a commercial haemagglutination assay for the detection of anti-HBs has reduced the test time from over one hour to approximately 25 min. increased sensitivity ten-fold without any prozoning, maintained specificity and reduced costs by 90%. The modification consists of diluting the reagent cells ten-fold; these are then added to dilutions of test serum in a V-well microplate.

Western blotting is a sensitive technique for the detection of anti-PlA1.

Western (immuno-) blotting was evaluated as a technique for anti-PlA1 detection, using untreated and chloroquine or low pH-treated platelets. Chloroquine-treated platelet membranes generated the cleanest blots, giving end-point titres of 4000-16,000 for three different anti-PlA1 sera. These titres were between three and eight doubling dilutions higher than those obtained in solid phase, ELISA or indirect immunofluorescence tests.

Mononuclear phagocyte assays, autoanalyzer quantitation and IgG subclasses of maternal anti-RhD in the prediction of the severity of haemolytic disease in the fetus before 32 weeks gestation.

In 40 cases of haemolytic disease of the fetus due to RhD immunization where the fetus required intrauterine transfusion, fetal packed cell volume was compared with the following parameters of maternal anti-D: (a) concentration, (b) IgG subclass, (c) activity in a macrophage binding assay, and (d) activity in a monocyte antibody-dependent cell mediated cytotoxicity (ADCC) assay. The anti-D concentration exceeded 4 iu/ml in all cases, correctly indicating the risk of haemolytic disease. A relationship between IgG subclass composition of the anti-D and severity of anaemia was not observed; IgG1, IgG3 and IgG1 + 3 antibodies were all detected.

Severe haemolytic disease in an infant born to an Rh(null) proposita.

A 35-year-old Brazilian woman (gravida 4, para 2) was delivered of a severely anaemic child whose cord red blood cells had a strongly positive direct antiglobulin test and who required two exchange transfusions within 24 h of birth. Because of the emergency of the situation and the lack of a local immunohaematology reference laboratory, the phenotype of the mother and the specificity of the relevant antibody could not be determined. Hence, compatible blood was not immediately available and the infant had to be given repeated exchange transfusions with incompatible group 0 Rh-negative blood.

Is there a wastage of resources due to non-specificity of anti-HIV ELISAs?

A library of anti-HIV ELISA 'grey-area' and repeatably reactive samples sent for confirmatory testing, were retested using a second technique, the modified (Fujirebio Gelatin Particle) agglutination test (MAT). On testing 224 grey-area reactive samples, only four were found to be reactive with this second test. On retesting a further 259 ELISA repeatably reactive samples, of which only 33 were confirmed to be anti-HIV-1, only 45 were reactive by MAT; these included the 33 confirmed as positive samples, thereby reducing the false-positive from 226 to 12.

Fibrin glue.

Fibrin glue is a topical biological adhesive, the effect of which imitates the final stages of coagulation. The glue consists of a solution of concentrated human fibrinogen which is activated by the addition of bovine thrombin and calcium chloride. The resultant clot aids haemostasis and tissue sealing and is completely absorbed during wound healing without foreign body reaction or extensive fibrosis.

Post-transfusion NANBH in the light of a test for anti-HCV.

The incidence of post-transfusion hepatitis (PTH) varies over an order of magnitude in different parts of the world. For example, prospective studies from Spain and the UK reveal rates of PTH of approximately 10 and 0.5% respectively.

Antibody to hepatitis C virus in blood donors found positive for other agents. II. Anti-HIV-1.

Stored serum samples from 24 blood donors confirmed positive for anti-HIV-1 were tested for antibody to hepatitis C virus (HCV). Those repeatedly reactive using the anti-HCV ELISA screening test were retested by the HCV recombinant immunoblot (RIBA). Risk-factors for the contraction of HIV infection that had been elicited at formal counselling sessions were evaluated in relation to HCV/HIV modes of infection.

Antibody to hepatitis C virus in blood donors found positive for other agents. I. Treponemal infection.

Stored serum samples from 169 blood donors found positive for TPHA were tested for antibodies to hepatitis C virus (anti-HCV) and to hepatitis B core (anti-HBc), as evidence of previous HBV infection, a condition known to be sexually transmissible. Only three donors were positive with a 'first generation' anti-HCV and all three failed to confirm with a recombinant immunoblot assay (RIBA). In contrast, 33 (19.

Blood component treatment: a retrospective audit in five major London hospitals.

A retrospective audit of 200 transfusion episodes involving the use of platelets or fresh frozen plasma (FFP) was performed in five hospitals in London. It examined the currently used practices of transfusion and assessed the appropriateness of blood component treatment. It was necessary to search for an excess of case notes to provide a sufficient number of patients for review.

Hepatitis C virus screening: UK Blood Transfusion Service on the threshold.

The implications of testing all blood donations in the UK for antibody to hepatitis C virus (HCV) are considered. Although the risks of serious liver disease arising from transfusion-transmitted HCV are relatively low in the UK, the cost of such screening will be high in terms of financial outlay and lost donations. In the UK, at least, screening of all blood donations for anti-HCV is unlikely to be as cost effective as screening for HBsAg or anti-HIV.

Characteristics of platelet concentrates, with particular reference to Autopheresis C Plateletcell: correlation between dMPV and other tests for platelet function.

The quality of platelet concentrates (PC) collected by the Autopheresis C cell separator was assessed in two Regional Transfusion Centres taking part in a multicentre study. This study also enabled the assessment of a new simple, rapid test of platelet function and comparison with more established tests, such as aggregation to adenosine diphosphate, as a tool for the quality testing of PC. The new test, based upon the measurement of mean platelet volume using automated haematological cell analysers, is rapid and uses the same samples as those used to estimate the platelet and leucocyte content of the concentrates.

Quality monitoring of haemapheresis platelet concentrates: sampling in EDTA helps with the standardization and improves the consistency.

At the North London Blood Transfusion Centre, all haemapheresis platelet concentrates (PC) are tested in duplicate by a Technicon H-1 analyser to provide accurate information on the cell separator performance and on the cellular content of packs before issue. Repeated counting on fresh samples (within 4 h) reveals spontaneous aggregation (SA), which causes inconsistency in the estimated platelet yields and invalidates the cellular indices. Preliminary work showed that sampling into EDTA eliminated SA.

An overview of current quality control procedures in platelet storage lesion and transfusion.

In brief the major tasks in quality monitoring of platelet concentrates are: (i) To ensure that the process is able to meet the product specifications. (ii) To steer the apheresis session and production laboratory towards prevention-oriented decisions. (iii) To provide data on where problems are likely to occur, helping to identify cause-and-effect relationships.

Low incidence of non-A, non-B post-transfusion hepatitis in London confirmed by hepatitis C virus serology.

To see whether the introduction of screening tests for post-transfusion non-A, non-B hepatitis (NANBH) in the UK would be worth while, the incidence of such hepatitis was assessed among patients receiving blood during operations at five hospitals served by the North London Blood Transfusion Centre. 387 patients, who each received blood or blood components from an average of 3 donors were followed up prospectively and blood samples were taken every 2 weeks for 3 months and then each month for a further 3 months. 229 patients also provided a sample at 12 months.

Development of non-Rh antibodies in volunteers stimulated for the production of hyperimmune anti-D.

At the North London Blood Transfusion Centre, red cells from accredited Rh-D-positive donors, matched for all antigens capable of inducing clinically significant antibodies, are used to stimulate immune plasma donors to achieve higher anti-D levels. Despite such careful matching, antibody to the relatively non-immunogenic M antigen developed in 3 out of 20 NN donors (15%) stimulated with M-positive cells. In general, good responders to the Rh antigen D are good responders to other red cell antigens; our report exemplifies the importance of using fully matched accredited red cells for immune stimulation and the need to perform thorough antibody screening after each stimulation.

A new qualitative variant of the RhE antigen revealed by heterogeneity among anti-E sera.

We have recently detected a new qualitative variant of the RhE antigen characterised by negative reactions with a minority of anti-E sera, and an inability of the relevant cells to completely absorb most, if not all, anti-E samples that we tested. In tube tests, using a two-stage enzyme technique, cells from the proposita (V.R.

Non-A, non-B hepatitis and the anti-HCV assay.

The successful cloning of a non-structural antigen from the genome of what is now designated as the 'hepatitis C virus' (HCV) has transformed an erstwhile diagnosis of exclusion for non-A, non-B hepatitis (NANBH). The assay has been validated against panels of known infectivity for NANBH and sera from haemophiliac patients treated either with virally inactivated or uninactivated factor VIII. The predictive value of the assay is being assessed clinically in prospective studies of post-transfusion hepatitis and by using laboratory techniques such as polymerase chain reaction.

Clearance of Rh D-positive red cells with monoclonal anti-D.

Two human monoclonal antibodies, one IgG3 and one IgG1, with anti-Rh D specificity, were tested for their ability to clear red cells. Samples of red cells from 12 D-positive subjects were sensitised in vitro with various amounts of antibody, the number of antibody molecules bound to the cells was estimated, and the cells were reinjected into the donor's circulation. Both antibodies mediated clearance but substantially fewer IgG3 than IgG1 antibody molecules were required to produce a given rate of clearance.

Lassa fever.

Lassa fever is an acute viral illness which causes considerable morbidity and mortality in West Africa. The risk of importing the disease into the UK is small but real, and it continues to be a worldwide concern among public health officials. This article summarizes its epidemiology and clinical presentation, and discusses current theories of its pathogenesis.