Reduction of HTLV-I-infected cells in blood by leukocyte filtration

Donors with repeated blood product discards for filtration problems, clots or hemolysis: Causes and follow-up

INTRODUCTION

Sanquin donor medicine department is informed when donations or their components are rejected. This can occur isolated or frequently. It is undesirable because the donations cannot be used and there may be an underlying medical cause. Based on regional approaches, a uniform procedure was developed.

METHODS

Information about whole blood, plasma- plateletpheresis donations from which one or more components were rejected for filtration time (>2 h), hemolysis or clots were extracted from blood bank information system. After rejection of two successive components or donations or total ≥3 the donor is contacted. Depending on the medical history and investigation by the family doctor, the donor carrier is re-evaluated. We looked for the causes of the discarded products and performed a survey among blood services regarding polices with discarded products.

RESULTS

One or more components from 1742 of about 2.2 million successful donations (0.08%) were rejected. The highest percentage of rejection was seen in plateletpheresis (1.5%), all for clots. No underlying medical causes were found. 24 whole blood donors were found to have sickle cell trait (SCT) and were permanently deferred. The policies for follow-up after discarded products or acceptance of SCT donors vary between the 16 blood banks. Six organizations do not follow-up donors and seven accept SCT for blood or plasma donation.

CONCLUSION

Informing donors with repeated discarded products avoids the non-use of donations. Causes of repeated discarded products can be found by follow-up of donors. The results of the survey indicate a large discrepancy in policies applied worldwide.

Reconsideration of blood donation testing strategy for human T-cell lymphotropic virus in Australia

BACKGROUND AND OBJECTIVES

Universal testing of blood donations for human T-cell lymphotropic virus (HTLV) in Australia may no longer be appropriate given the low prevalence of HTLV infection and the mitigating effect of universal leucodepletion for cellular components. This study aimed to determine the most appropriate HTLV testing strategy using the Risk-Based Decision-Making Framework for Blood Safety.

MATERIALS AND METHODS

The risk of HTLV transfusion-transmission using three testing strategies (universal, new-donor and no testing) and cost-effectiveness of the first two strategies were assessed using adaptations of published mathematical models.

RESULTS

The overall prevalence for 2004-2014 was three HTLV-positives per million donations. It was estimated that annually, universal testing incurred a cost of approximately AUD $3 million and prevented 83 HTLV-positive cellular components from being issued, and new-donor testing cost approximately $225 000 and prevented 81 components. The number of cases of transfusion-transmitted HTLV and HTLV-associated disease prevented per year by universal and new-donor testing was essentially equivalent. According to preset risk thresholds, the risk of transfusion-transmission was negligible for universal and new-donor testing, and minimal without testing.

CONCLUSION

Transfusion-transmission of HTLV is a minimal risk in Australia even without testing. However, any revision of testing strategy must consider not only risk and cost-effectiveness, but also stakeholder, ethical and regulatory perspectives. Considering all relevant criteria, new-donor testing is judged the optimal strategy because it is able to achieve almost the same outcomes as universal testing, at a fraction of the cost.

Leukocyte Reduction's Role in the Attenuation of Infection Risks among Transfusion Recipients

Despite advances in the screening of donated blood for infectious agents, the risk of transmitting viral, bacterial, and protozoal infections, as well as newly emerging diseases, via transfusion persists. A complementary approach is leukocyte reduction (LR), the removal of leukocytes from donated blood by filtration. Published evidence, establishing the benefit of LR in reducing the risk of febrile nonhemolytic reactions, cytomegalovirus transmission, and human leukocyte antigen alloimmunization has led to its use for some time for the care of immunosuppressed and other individuals considered to be at high risk for such complications. Recent literature suggests that LR may be effective in reducing the risk of transmission of a number of additional transfusion-transmitted infectious agents, including herpesviruses, retroviruses, bacteria, protozoa, and prions. There is also evidence that LR may reduce the risk of transfusion-related immunomodulation, further contributing to protection against infections that would complicate treatment. With the mounting evidence of potential benefit, a number of countries, as well as many hospitals and blood centers in the United States, have adopted a policy of performing LR for all donated blood. Physicians who care for immunosuppressed patients and those who are responsible for institutional infection-control practices should remain informed of the growing body of literature on LR.

Evaluation of HTLV-I removal by filtration of blood cell components in a routine setting

BACKGROUND

WBC depletion by filtration may prevent the transmission of HTLV-I, which requires cell-to-cell contact. The removal of HTLV-I-infected cells in routinely filtered blood cell components was measured.

STUDY DESIGN AND METHODS

The study was conducted in Martinique where systematic screening for HTLV-I and -II and universal leukoreduction are mandatory. HTLV-I was quantified by use of real-time PCR in 8 RBC units and 4 PLT concentrates before and after filtration. HTLV-I proviral load in PBMNCs was determined in five of the eight HTLV-I-infected blood donors.

RESULTS

The amount of MNC-associated HTLV-I DNA in RBC units before filtration was 21 x 10(6)+/- 29 x 10(6) copies (mean +/- SD). HTLV-I was detected in 4 of 8 RBC units after filtration, with a number of copies in the MNC fraction ranging from 20 to 140, following a 4.9 to 5.8 log reduction. Flow cytometry analysis performed in 2 of the filtered RBC units containing detectable HTLV-I showed suboptimal and out-of-range leukoreduction (0.56 x 10(6) and 1.22 x 10(6) residual WBCs). HTLV was not detected in filtered RBCs from the blood donor with the highest percentage of HTLV-I-infected PBMCs (9%).

CONCLUSION

This study confirms that HTLV-I-infected cells can be detected in filtered blood cell components and shows that optimal leukoreduction is critical for HTLV-I removal.

Inline-filtration

BACKGROUND

Routine leukocyte-depletion (LD) of cellular blood products, and even plasma, is currently being implemented in most European countries, as a result of the fear that the variant Creutzfeldt-Jakob-disease (vCJD) might be transmissible by transfusion. However, not only is the scientific evidence supporting such a notion scarce, but the benefits of applying this procedure to all patients also remain unfounded.

METHODS

A MEDLINE-research for studies dealing with the indications for LD was performed. In addition, the guidelines and recommendations of national and international health authorities were scrutinized.

RESULTS

To date,the only proven benefit of LD that can be applied to all patients is the reduction of non-hemolytic febrile transfusion reactions. In addition, LD reduces HLA-immunization and platelet refractoriness in multi-transfused patients. In immunocompromized patients, LD reduces transfusion-transmitted CMV-disease. Furthermore, a minority of 5-10% of transfusion-related-acute-lung-injury cases can be prevented by LD. However, the potential of reducing the immunomodulating effects of transfusion such as postoperative infection, cancer-recurrence-related or overall mortality and of reducing septicemia due to bacterial contamination is still at issue. AIDS patients do not benefit from LD, at least. The suitability of LD for preventing the transmission of vCJD is at best hypothetical. Potential risks of LD like increased leakages have not been taken into account adequately to date.

CONCLUSIONS

At present, the scientific evidence does not justify the introduction of LD as a routine measure. In times of limited health care resources, this costly procedure might limit access to medical services with proven effectiveness and efficiency. In addition, the loss of 5-10% of the red cell pool is predicted to lead to more blood supply shortages than previously seen.

Persistence of HTLV-I in blood components after leukocyte depletion

The human T-cell leukemia virus HTLV-I is a transfusion-transmissible retrovirus targeting T lymphocytes for which screening is not currently undertaken in United Kingdom blood donors. The introduction of universal leukocyte depletion (LD) of the United Kingdom blood supply raises the question as to the degree of protection afforded by this procedure against HTLV-I transmission by blood components. HTLV-I viral DNA removal by leukocyte-depleting filters was assessed in units of whole blood and platelets by real-time quantitative polymerase chain reaction (PCR) and by nested PCR for HTLV-I Tax DNA. We examined HTLV-I removal by LD filters using a model system of blood units containing exogenous spiked HTLV-I-positive MT-2 cells at a relevant concentration and whole blood donations from asymptomatic HTLV-I carriers. T-lymphocyte removal was assessed in parallel by measurement of endogenous subset-specific CD3 mRNA. In the MT-2 model system we observed 3.5 log(10) to 4 log(10) removal of HTLV-I Tax DNA by filtration of whole blood and 2 log(10) to 3 log(10) removal across platelet filters with 13 of 16 whole blood and 8 of 8 platelet units still positive after filtration. Despite 3 log(10) to 4 log(10) viral removal, HTLV-I Tax DNA could be detected after whole blood filtration in asymptomatic carriers with viral loads above 10(8) proviral DNA copies/L. T-lymphocyte removal was also between 3.5 log(10) and 4.5 log(10). HTLV-I provirus removal was incomplete in the model system and in asymptomatic carriers with viral loads greater than 10(8) copies/L. These results suggest that LD alone may not provide complete protection from HTLV-I transmission by transfusion.

Malignancy: Human T-Cell Lymphotropic Virus Type I and Adult T-Cell Leukaemia/Lymphoma

Adult T-cell leukaemia/lymphoma (ATLL) was first identified in Japan in 1977 [1,2]. The causative agent, the human T-lymphotropic virus type I (HTLV-I), was isolated 3 years later by Gallo's group from a patient initially diagnosed as having mycosis fungoides but subsequently reclassified as a case of ATLL [3]. Since this time, much has been discovered about the molecular pathogenesis of the disease. Despite this, treatment of ATLL remains disappointing and the prognosis of acute and lymphoma types poor. In the United Kingdom, cases of ATLL are mainly restricted to people of Afro-Caribbean descent but the disease is of general importance because ATLL has also been reported in non-endemic areas and may possibly spread into other populations via blood transfusion as blood donors in the UK are currently not screened for HTLV-I.

Update on leucocyte depletion of blood components by filtration

It has long been recognized that allogenic leucocytes from donor blood are responsible for serious untoward effects in some transfused patients such as alloimmunization, febrile reactions, platelet refractoriness, transfusion associated acute lung injury, immunosuppression as well as transmission or reactivation of viruses such as CMV, HTLV or EBV. Leucocytes are also known to accelerate the rate of storage lesion. The optimal method to remove leucocytes from blood components has been shown to be filtration. However, many variables exist in the properties of leuco-depletion filters (material, composition, surface charge, mechanisms of leucocyte entrapment), the blood components to be filtered (composition, age), and the filtration method (pre- or post-storage, priming and rinsing, temperature, flow rate). In this paper principles of filtration and subsequent logistic consequences will be discussed. It is recommended to carefully select a filter for a specific blood component and to perform leuco-depletion procedures under controlled conditions according to validated methods meeting Good Manufacturing Practice (GMP) and Good Laboratory Practice (GLP).

Lack of Clinically Significant Contact System Activation During Platelet Concentrate Filtration by Leukocyte Removal Filters

When blood (plasma) contacts certain foreign surfaces, factor XII can activate and trigger a series of reactions leading to cleavage of kininogens with subsequent release of bradykinin. In this study, we investigated two different widely used leukocyte removal filters, Pall PXL8K (A) and Asahi PLS-5A (B), to test whether clinically significant contact activation occurred during leukodepletion of platelet-rich plasma (PRP). Kininogens were measured by particle concentration fluorescence immunoassay (PCFIA), which can detect cleavage of high and low molecular weight kininogens (HK and LK), the parent molecules of bradykinin, to determine if contact activation had occurred. A slight, nonsignificant decrease in HK and LK was observed with filter A after the first 5 mL was filtered that returned to prefiltration levels by the end of the filtration. Specific TotK (the combined measurement of HK and LK heavy chains divided by plasma protein concentration) showed a small, significant decrease with filter A after the first 5 mL of platelet concentrates was filtered that returned to prefiltration levels by the end of the filtration. There were no significant increases or decreases in the cleaved kininogen index (CKI), an index of HK proteolytic activation or HK and LK destruction (with release of bradykinin). These data suggest that small amounts of both HK and LK initially adsorb to filter A and then desorb, primarily intact. These data also indicate that no significant contact activation, as measured by PCFIA, occurs during leukodepletion of platelet concentrates with either filter A or B.

Lack of Clinically Significant Contact System Activation During Platelet Concentrate Filtration by Leukocyte Removal Filters

When blood (plasma) contacts certain foreign surfaces, factor XII can activate and trigger a series of reactions leading to cleavage of kininogens with subsequent release of bradykinin. In this study, we investigated two different widely used leukocyte removal filters, Pall PXL8K (A) and Asahi PLS-5A (B), to test whether clinically significant contact activation occurred during leukodepletion of platelet-rich plasma (PRP). Kininogens were measured by particle concentration fluorescence immunoassay (PCFIA), which can detect cleavage of high and low molecular weight kininogens (HK and LK), the parent molecules of bradykinin, to determine if contact activation had occurred. A slight, nonsignificant decrease in HK and LK was observed with filter A after the first 5 mL was filtered that returned to prefiltration levels by the end of the filtration. Specific TotK (the combined measurement of HK and LK heavy chains divided by plasma protein concentration) showed a small, significant decrease with filter A after the first 5 mL of platelet concentrates was filtered that returned to prefiltration levels by the end of the filtration. There were no significant increases or decreases in the cleaved kininogen index (CKI), an index of HK proteolytic activation or HK and LK destruction (with release of bradykinin). These data suggest that small amounts of both HK and LK initially adsorb to filter A and then desorb, primarily intact. These data also indicate that no significant contact activation, as measured by PCFIA, occurs during leukodepletion of platelet concentrates with either filter A or B.

Blood transfusion in beta thalassaemia major

Conventional treatment of beta thalassaemia major is based on regular blood transfusion from early childhood. Maximum effectiveness of transfusion therapy depends on the following. (1) Availability of safe blood. Donation programmes should aim at retaining repeat donors, who carry decreased risk of transmitting blood-borne infections. Donors should be screened with laboratory tests performed to the highest possible standard of quality. Selection of safe donors can be improved by the adoption of questionnaires containing direct questions on risk factors for transfusion transmissible infections. (2) Use of good quality red blood cells, which should be leucodepleted, preferably by filtration, that can be carried out at the bedside. (3) Regular evaluation of blood transfusion indices, including mean level of haemoglobin maintained, annual blood requirement, daily haemoglobin fall, mean transfusion interval, transfusion reaction rate. This can be assisted by the use of a computerized patient record. (4) Maintenance of a permanent record of the patient's blood group genotype (including at least Rh, Kell, Kidd and Duffy systems) and any red cell antibodies that develop. This is mandatory to ensure optimal survival of transfused red cells. (5) Continuous monitoring of transfusion transmissible infections. (6) Vaccination against hepatitis B of all suitable patients. (7) Intensive iron chelation. This should be done by regular subcutaneous administration of desferrioxamine B. Oral chelators, which are currently under laboratory and clinical evaluation, are not yet available for general use.

Reducing the infectivity of blood components--what we have learned

The safety of the nation's blood supply has improved over the last several years as a result of more intensive donor screening and viral testing. Concurrently, there has been more judicious use of blood components. Although the risk is small, transmission of blood borne viruses, bacteria and parasites can occur. Investigators have studied a myriad of processes for pathogen depletion and/or inactivation, including the use of chemicals, extended storage, filtration, heating, irradiation, photochemicals and washing. Pasteurization, methylene blue and solvent-detergent processes have been introduced in parts of Europe for improving the safety of plasma used for transfusion. The FDA is reviewing a license application for the solvent-detergent process. For red cells, use of highly efficient leukodepletion filters is believed to be equivalent to antibody testing for the prevention of CMV disease transmission. Otherwise, no successful treatments have yet been identified for red cells or platelets. Several photochemicals, which may be useful for treating these components, are being studied. However, there appear to be trade-offs between the extent of pathogen inactivation, platelet or red cell damage, and genotoxicity. These as well as other biological parameters and operational issues will need to be further evaluated before implementation can be considered.

Sequence analysis of cDNA derived from reticulocyte mRNAs coding for Rh polypeptides and demonstration of E/e and C/c polymorphisms

RNA derived from enriched reticulocytes of Rh-phenotyped donors was isolated, reversely transcribed into cDNA and amplified with Rh-specific primers by polymerase chain reaction. Nucleotide sequence analysis of the entire coding region of the Rh cDNAs was carried out. Four types of cDNAs were identified, tentatively designated as RhSCI, RhSCII, RhSCIII and RhSCIV. Comparison of RhSCII with RhSCI (identical to the previously reported RhIXb/30A cDNA), showed single base pair difference. Since RhSCI and RhSCII were found to be related to the presence of E or e antigen, respectively, the P226A amino acid polymorphism appears to be the genetic basis of the E/e polymorphism. RhSCIII was demonstrated to be a transcript derived from the RhD gene, with 35 amino acid substitutions as compared to RhSCI. RhSCIV was found to be present only in RhC-positive individuals, indicating that RhSCIV encodes a polypeptide carrying the C antigen. Six nucleotide changes, resulting in four amino acid substitutions W16C, L60I, N68S and P103S, were observed between RhSCII and RhSCIV, probably representing the C/c polymorphism.