Blood banks meet the paradox of Gabriel's Horn: what are the options to maintain supply as demand decreases?

Blood services worldwide have observed a decline in the demand for red blood cells (RBC). Despite this general decline, the demand profile has changed significantly with the demand for O D negative RBCs being maintained; whereas B D positive and AB D positive RBC demand has been reduced. In 2015, the blood type O D negative was seen in 6·3% of the combined first time donors among the five American Blood Centres involved in this study and 7·4% of first time Australian donors in 2014/2015, whereas O D negative distributions accounted for 10·5% of all red cell units issued by the American centres and 13·9% by the Australian centres. Inventory can therefore be of sufficient overall quantity but may not be adequate for the demand for units with specific blood types. Recruitment of new donors may need to become more targeted and/or financial or inventory control measures could also be required to ensure inventory matches demand. Blood Services will need to consider the available options in order to ensure that sufficiency of supply is secure and the donor panel is optimised to meet the new demand paradigm.

Practical guidelines for applying statistical process control to blood component production

Legislation, guidelines and recommendations for blood components related to statistical process control (SPC) and the selection of a quality monitoring (QM) sampling regimen are subject to misinterpretation and lack practical guidance on implementation. The aim of this article is: to review and interpret applicable European legislation and guidelines and to develop an SPC strategy that meets these requirements; and to provide practical guidance on the selection and application of appropriate techniques and the interpretation of resultant blood component QM data. A methodology is presented which utilizes: an algorithm to select an appropriate quality-monitoring strategy for the blood component parameter under consideration; a range of straightforward, validated SPC techniques for variable data and an assessment of process capability (Cpk) and blood component parameter 'criticality' to determine the sampling regimen. The methodology was applied to routine National Health Service Blood and Transplant (NHSBT) blood component data for 2005-2006. Cpk values ranged from 0.22 to >3 and their predicted non-conformance rates were close to those observed (23 to <0.001%). Required sample size ranged from 0.01 to 10%. Chosen techniques identified significant deviation from 'as validated' performance within an appropriate time-scale. Thus the methodology was straightforward to apply and prompted the choice of a clinically and operationally appropriate sampling regimen and analysis for each blood component parameter. This evidence-based, targeted use of SPC for blood component monitoring provides an essential focus on processes with a low capability in achieving their specifications.

Blood pack fault monitoring

BACKGROUND AND OBJECTIVES

The National Blood Service (NBS) has recalled blood components as a result of manufacturing faults, or defective blood pack component parts leading to the possibility of an 'open' system. There has been an increase in the complexity of blood packs as a result of leucodepletion, sample diversion and sampling. The NBS implemented a mechanism to collate and analyse blood pack faults as a safety and quality initiative in conjunction with blood pack manufacturers.

MATERIALS AND METHODS

Standard reporting forms were produced and implemented at all Centres. The forms were collated and analysed using statistical analysis software. Control charts were used to identify trends for specific faults, which were resolved with the relevant manufacturer.

RESULTS

The overall defect rate per million for the three main blood pack manufacturers used by the NBS for the respective periods 2001, 2002 and 2003, were as follows: Manufacturer A, 1076, 1396 and 954; Manufacturer B, 1496, 1301 and 2169; and Manufacturer C, 1871, 1253 and 1392.

CONCLUSIONS

Monitoring and analysis of blood pack faults has resulted in the identification and rectification of specific problems associated with blood pack manufacture and use. Close collaboration with manufacturers has enabled effective remedial action. Wider collation of data would provide an early warning of potential areas of concern.

The development of a national standardized approach for the enumeration of residual leucocytes in blood components

BACKGROUND AND OBJECTIVES

The UK Blood Transfusion Services implemented universal leucocyte depletion of the blood supply in November 1999. To provide statistical process monitoring of these processes, automated methods were introduced to count residual leucocytes (white blood cells) in blood components.

MATERIALS AND METHODS

Initially in the National Blood Service (NBS) England, protocols were standardized on the use of LeucoCount reagents with either Becton-Dickinson or Beckman Coulter flow cytometers.

RESULTS

Standardization of protocols resulted in a decreased intersite variability of red cell samples (from 36% to 9% at a level of 11 and 10 cells/ micro l, respectively), and 100% of sites (n = 11) fulfilled the validation criteria. However, we also evaluated the use of alternative reagents with the result that reagents from either Becton-Dickinson or Beckman Coulter, used on either a Becton-Dickinson or Beckman Coulter flow cytometer, passed our validation criteria.

CONCLUSIONS

It is critical to include samples from filtered products containing white blood cells in validations of leucocyte enumeration methodology, as results may differ between methods using these samples but not using spiked or fixed material. Standardized gating strategies and optimization methods for flow cytometers are critical for obtaining equivalent results with different reagents and instruments.

The effect of leucocyte depletion on the quality of fresh-frozen plasma

The aim of this study was to evaluate the quality of leucodepleted (LD) fresh-frozen plasma (FFP) produced using one of five whole blood filters (Baxter RS2000 & RZ2000, NPBI T2926, Macopharma LST1 and Terumo WBSP) or two plasma filters (Pall LPS1 and Baxter FGR7014). Whole blood or plasma was filtered within 8 h of collection at an ambient temperature. Samples were taken pre- and post filtration for analysis of coagulation factors and complement activation (n = 7--12 for each type of filter). All filtered units (209--286 ml) contained < 5 x 10(6) residual leucocytes and < 30 x 10(9)/l platelets. Statistically significant losses of factors V, VIII, IX, XI and XII and increases in markers of coagulation activation were observed (0--21%), which were dependent on filter type. None of the filters had a significant effect on von Willebrand factor (VWF) multimeric distribution or the activity of VWF and factors II, VII or X. The effect on levels of C3a appeared to be related to the filter surface charge: positively charged filters resulted in C3a generation, whereas negatively charged resulted in C3a removal. None of the observed changes are likely to be clinically significant unless subsequent processing of plasma (such as pathogen inactivation) results in further losses of coagulation factors.

Monitoring universal leucodepletion performance: the current issues within components production and testing

The UK NBS completed the introduction of universal leucodepletion in November 1999. This involved the implementation of new methods of production, testing and monitoring, the development of which is still ongoing. Whilst important lessons have been learnt, much remains to be achieved in respect of quality improvement through standardisation of procedures, processes and product modifications to improve safety/efficacy of therapeutic blood components. Since the introduction of universal leucodepletion, many changes in component production and testing have occurred. The primary goal of this report is to review the level of standardisation and harmonisation currently achieved for low leucocyte counting within the NBS and discuss remedial actions undertaken to improve the standard of blood component production and quality monitoring and to highlight some of the related issues which are currently being worked on. The following issues are discussed.

No evidence of infection with porcine endogenous retrovirus in recipients of encapsulated porcine islet xenografts

Transplantation of pig tissues into humans has the potential for cotransferring pig infections. Knowledge of the epidemiology of pig infections transmissible to humans allows the development of risk limitation strategies at the source herd level, but potentially infectious pig endogenous retrovirus (PERV) is ubiquitous in all domestic pigs and therefore is not avoidable. Using a specific and sensitive RT-PCR and nested PCR for PERV nucleic acids with primers, the screening of pigs from New Zealand herds for the presence and expression of the PERV was conducted. The presence of PERV proviral DNA (pol and env region) and viral RNA was demonstrated in all tested pig tissues including pancreas, liver, spleen, brain, heart, and PBMC. Using the same assays it was established that different tissues (liver, spleen, and heart) of nude and nonobese diabetic (NOD) mice previously transplanted with nonencapsulated pig islets were PERV DNA and RNA negative. Alginate polylysine capsules prepared with encapsulated pig islets were tested for possible leakage of viral particles or viral nucleic acids. RNA was extracted from the supernatant of viable encapsulated pig islet cells grown in culture for 2 months. No evidence of PERV RNA or of cellular nucleic acids could be found. Two adult type I diabetic subjects were transplanted with 1 x 10(6) neonatal pig islets encased in alginate capsules into the peritoneal cavity. One patient was immunosuppressed. Both showed evidence of graft function (up to 34% reduction in insulin dose, corresponding increase in serum pig C-peptide) for up to 2 years. DNA and RNA were extracted from PBMC and blood plasma of both patients at 19 months posttransplant. No evidence of PERV proviral DNA or RNA could be detected. Piglet islets contain PERV DNA and RNA, but this does not traverse the capsules used or produce any evidence of infection in nude and nonobese diabetic (NOD) mice or humans.

Leucodepletion process performance variation: is it dependent on the batch of filters, the processing centre or the counting technology?

The aim of this retrospective study was to determine whether variations in the enumerated white cell contamination of leucocyte-depleted products was caused by the filter batch, the processing centre or by counting technology related issues. The influence of donor variation is also considered. The results suggest that for some red cell processes, variation is mainly the result of counting technology differences. Other products do not display similar trends though all leucodepletion processes may give rare high white count failures due to donor related issues, though defective filter batch cannot be excluded requiring continual review.

UK strategy for process qualification/validation: from concept to practical implementation

In this communication, after a brief review of current requirements of various stages of leucodepletion qualification/validation processes, we provide some practical examples for the usefulness of long term validation programme for process improvement. It is hoped that the experience gained from this process qualification/validation enhances the awareness to key variables that can influence the overall outcome of filtration programme.

The UK strategy for monitoring universal leucodepletion

This summary manuscript deals with the NBS approach to quality monitoring of universal leucodepletion based on representative sampling. There is also a brief discussion on the failure rate and potential causes for the inter site variations in white cell enumeration by current methods.