HLA immunization of haemodialysed patients in the transfusion and the erythropoietin eras

The frequency of transfusions and the development of HLA alloimmunization in the years 1986 and 1995, representing the 'transfusion era' and the 'erythropoietin era', have been compared. The introduction of erythropoietin was found to reduce the need for transfusion in haemodialysed patients on the waiting list from 65.2% to 5.7%. The elimination of transfusions resulted in a decrease in HLA immunization from 56.5% to 35%. In those patients who were still immunized, antibody production was probably caused either by immunomodulation or by transfusions given to treat complications. Erythropoietin could be used instead of transfusions in almost all cases, except for complications involving severe bleeding.

Transfusion medicine: looking to the future

The evolution of transfusion medicine into a clinically oriented discipline emphasising patient care has been accompanied by challenges that need to be faced as specialists look to the future. Emerging issues that affect blood safety and blood supply, such as pathogen inactivation and more stringent donor screening questions, bring new pressures on the availability of an affordable blood supply. Imminent alternatives for management of anaemia, such as oxygen carriers, hold great promise but, if available, will require close oversight. With current estimates of HIV or hepatitis C viral (HCV) transmission approaching one in 2000000 units transfused, keeping to a minimum bacterial contamination of platelet products (one in 2000) and errors in transfusion, with its estimated one in 800000 mortality rate, assume great urgency. Finally, serious difficulties in blood safety and availability for poor, developing countries require innovative strategies and commitment of resources.

Transfusion alternatives

The use of biological products for transfusion is limited not only by availability but also by public concerns for safety. Pharmacological interventions are being used to address these issues. This article reviews the history of transfusions, and assesses the current and future hematopoietic substitutes and their impact on blood supply and safety.

Molecular biology in transfusion medicine: current applications and future practice

Alloantibodies to blood group antigens are produced because there are differences between the blood group antigens on recipient and donor (or mother and fetus) red blood cells. Historically and currently, blood group antibodies and antigens are detected by hemagglutination, which can require considerable skill. Over the past 2 decades, there has been an astounding pace of growth in the field of molecular biology techniques and even more recently in the understanding of the basis of many blood group antigens and phenotypes. Thus, we are now able to consider identification of blood group antigens in genetic terms and identification of blood group antibodies using molecular approaches. Indeed, this knowledge is being applied to help resolve some long-standing clinical problems that cannot be resolved by classic hemagglutination. This article reviews our current knowledge of molecular approaches for identifying blood group antigens and antibodies as applied to transfusion medicine.

Transfusion-transmitted hepatitis B virus infection in the UK: a small and moving target

BACKGROUND AND OBJECTIVES

Transfusion-transmitted hepatitis B virus (TT-HBV) infections, when analysed in detail provide information about the nature and relative frequency of the sources of infectious donations. These cases are therefore used to inform blood safety strategies. This study updates previous reviews of the causes of TT-HBV in order to determine whether a change may have occurred in recent years.

MATERIALS AND METHODS

Cases of TT-HBV reported during 1998-2001 were reviewed and the nature of the infectious donations described. These cases were compared to a previously published case series reported during 1991-97.

RESULTS

Six cases of TT-HBV have been reported in the UK between 1998 and 2001. All were the result of infectious donations collected from donors with acute HBV infection. This is in contrast to the series reported during 1991-97 when only three of 14 similar cases were caused by acute infections in donors, with the majority of incidents being the result of chronic infection in donors.

CONCLUSIONS

There appears to have been a change in the relative importance of acute and chronic HBV infection in blood donors in causing TT-HBV infections. Improvements in the sensitivity of HBsAg assays and/or a decrease in the prevalence of chronic HBV infection in blood donors could explain this observation. This change may have implications for strategies to reduce the risk of TT-HBV infection.

Sensitization 2001

1. The rate of transfusion decreased from 64% in 1992 to 36% in 2000. This need for transfusions continued despite the introduction of erythropoetin. Females were transfused more frequently than males. SLE patients were transfused more often than those with other diseases. 2. Transfusions no longer had a beneficial effect on the outcome of transplantation, but rather with more transfusions, the graft outcome became lower, as might be expected. 3. Rejection of a kidney transplant had the strongest effect on sensitization, followed by transfusion and then pregnancies. Females were more susceptible to sensitization than males. Although non-transfused males should not have been sensitized, as many as 13% were reported to have antibodies. As many as 20% of nulliparous females without transfusions also were reported to have antibodies. 4. SLE patients were most often sensitized among patients with various diseases. Females of all diseases were more sensitized than males. 5. Unsensitized regraft patients had a 3% lower 3-year graft survival than unsensitized first graft patients. Among sensitized patients, regraft patients had a 4% lower graft survival than sensitized first graft patients. 6. Patients with polycystic kidney disease had the highest 3-year graft survival in both the sensitized and non-sensitized patients. Sensitization to a PRA level of less than 50% was not detrimental to patients with all the various diseases. 7. For cadaver donor regraft patients, HLA-DR mismatch had a greater effect than AB mismatch. There was a 10 percentage point lower 3-year graft survival in cadaver donor regraft patients mismatched for 2 DR antigens than mismatched for 0 DR antigens. 8. For living donor transplants, regrafts from 0 AB or 0 DR mismatched transplants had the same graft survival as first transplants.

Advances and dilemmas in recombinant blood products

The need to find safer blood products escalated in July 1982 with the first report of AIDS in a person with hemophilia. By 1985, approximately 10,000 people with hemophilia were infected with HIV and manufacturers were providing products that had been treated for viral inactivation. Approximately 8000 people with hemophilia have died in the AIDS epidemic, and approximately 2172 are surviving with HIV chronicity. The number of deaths are an enormous loss in a tightly knit and highly organized hemophiliac community whose activism brought about the Ricky Ray Hemophilia Relief Act. These 8000 lives will not be forgotten. The search for safer products, such as recombinant DNA technology products, is ongoing. Of persons using recombinant products in the United States, 61.3% have hemophilia A and 54.8% have hemophilia B. To meet the coagulation needs of the hemophilia population, it can be expected that innovative delivery models will emerge in the United States and globally.

Declining value of preoperative autologous donation

BACKGROUND

Preoperative autologous blood donation (PABD) has been shown to decrease allogeneic blood transfusion requirements in major elective surgery. Changes in transfusion practice motivated an examination of blood use from 1993 to 2000 of patients participating in the Héma-Québec PABD program.

STUDY DESIGN AND METHODS

Blood donation and transfusion, type of surgery, and demographic characteristics were prospectively entered into a computer database for patients participating in the Héma-Québec PABD program.

RESULTS

Autologous donations represented from 0.8 to 2 percent of total blood collections and have declined by 26 percent after peaking in 1995. The mean number of units collected per patient declined, as did the number of units transfused per patient and the utilization rate. For radical prostatectomy, knee replacement surgery, hip replacement surgery, and scoliosis, utilization rates were 72, 60, 83, and 78 percent in 1993 compared with 50, 50, 58, and 58 percent in 2000, respectively. In 2000, 18 percent of patients were receiving a 1-unit autologous transfusion. Depending on the surgical procedure, 85 to 95 percent of patients avoided allogeneic transfusion; this did not change significantly from 1993 to 2000.

CONCLUSION

Patients participating in the PABD program successfully avoided allogeneic transfusion in over 85 percent of cases. However, declining utilization rates and frequent 1-unit transfusions demonstrate the decreasing utility of PABD over time.

Changing scenario of transfusion-related viral infections

OBJECTIVE

To study the changing incidence of blood transfusion-related viral infections consequent to compulsory screening of blood and greater awareness of the problem, over the last five years.

METHODS

This is a cross-sectional study carried out at Medical College, Calcutta. Three groups each consisting of 100 subjects were selected for this study. Group A comprised multiple transfused patients who have also received transfusion before 1995. Group B comprised patients who had received transfusions only since 1995. Group C comprised of control patients who have never been transfused. The incidence of HBsAg +ve, anti-HCV +ve and HIV +ve cases were calculated and expressed as percentages and compared using the chi square test.

RESULTS

The incidences of HBsAg +ve and anti-HCV +ve cases in the three groups were 20% and 16% in Group A, 7% and 6% in Group B and 4% and 2% in Group C. The difference between Group A and Group B were statistically significant.

CONCLUSION

The incidence of HBsAg and anti-HCV positive cases among the multi-transfused has decreased over the last five years.

Mutation databases and other online sites as a resource for transfusion medicine: history and attributes

Recent advances in molecular biology and technology have provided evidence, at a molecular level, for long-known observations that the human genome is not unique but is characterized by individual sequence variation. At the present time, documentation of genetic variation occurring in a large number of genes is increasing exponentially. The characterization of alleles that encode a variety of blood group antigens has been particularly fruitful for transfusion medicine. Phenotypic variation, as identified by the serologic study of blood group variants, is required to identify the presence of a variant allele. Many of the other alleles currently recorded have been selected and identified on the basis of inherited disease traits. New approaches document single nucleotide polymorphisms that occur throughout the genome and best show how the DNA sequence varies in the human population. The primary data dealing with variant alleles or more general genomic variation are scattered throughout the scientific literature and only within the last few years has information begun to be organized into databases. This article provides guidance on how to access those databases online as a source of information about genetic variation for purposes of molecular, clinical, and diagnostic medicine, research, and teaching. The attributes of the sites are described. A more detailed view of the database dealing specifically with alleles of genes encoding the blood group antigens includes a brief preliminary analysis of the molecular basis for observed polymorphisms. Other online sites that may be particularly useful to the transfusion medicine readership as well as a brief historical account are also presented.

The United Kingdom National External Quality Assessment Scheme (blood transfusion laboratory practice): trends in proficiency and practice between 1985 and 2000

Proficiency in blood transfusion laboratory practice has improved over the last 15 years (1985-2000). Error rates for ABO grouping have fallen from 0 x 19 to 0 x 02% (P = 0 x 003). A similar trend is evident for antibody screening, with error rates for false negative antibody screens falling from 3 x 2 to 0 x 5% (P < 0 x 001), and for antibody identification, for sera containing a single alloantibody, with error rates falling from 8 x 8% to 0 x 9% over the last 10 years (P < 0 x 001). Proficiency in serological crossmatching to detect clinically significant non-ABO incompatibilities (other than Kidd), has also improved (P < 0 x 001). However, error rates for RhD grouping have not changed and there has been a recent decline in proficiency in detecting weak ABO incompatibilities and Kidd antibodies with heterozygous cells. Procedures for pretransfusion testing have also been rationalized over this time. The indirect antiglobulin test (IAT) is used in isolation by 73% of laboratories for antibody screening, and 10% rely on the direct room temperature (DRT), immediate spin (IS) crossmatch in the absence (current and/or historical) of clinically significant antibodies. Despite the improvements in error rates that have occurred alongside the rationalizations, there is still evidence of noncompliance with current published BCSH guidelines and manufacturers' instructions.

[Challenges of transfusion medicine]

Transfusion medicine has the logic of a therapeutic chain applied to labile blood components and cell therapy products, within a coherent structure, such as the recently created Etablissement français du sang. Faced to the threat of emerging--sometimes hypothetical--transfusion risks, such as the possible transmission of BSE by blood transfusion, the precaution principle requires developing strategies to reduce labile blood components consumption, by strictly defining the framework of blood transfusion prescription and encouraging the search for red blood cell and platelet substitutes. In the field of alternatives to labile blood components, research has however yielded few results. The future of transfusion medicine lies in biotechnology: cell (and gene) therapy will become part of novel therapeutic strategies for the treatment of numerous pathologies in man. Transfusion medicine will have to consider the significant advances achieved over the last few years in the field of multipotent stem cells. Transfusion medicine will thus find its place in the promising field of innovating therapies.