| Objectives:Leukocyte reduction filters are widely used nowadays in transfusion practice. However, there is no standard rule of leukocyte reduced blood components, leading to some cases of indiscriminate leukocyte filtration, which reduces the function and effectiveness of leukocyte reduced blood in clinical transfusion. This is a problem that needs to be solved in current transfusion medicine. Thus, the main objective, as well as the novelty of this research, is to systematically study the use and methods of leukocyte reduction currently in China for main blood components, and to provide experimental proof for scientific management and reasonable utilization of leukocyte reduced components.Content:By focusing on the abuse of leukocyte reduced fresh frozen plasma (FFP), the necessity of leukocyte reduction of plasma preparation was investigated, and the leukocyte filtration effect of some kinds of domestic plasma filters was evaluated. Given the many platelet preparations and unclear indications of their leukocyte filtration, the effect of filtration on the platelet preparations was observed, before platelet preparations that were suited to platelet filtration were selected. As studies on leukocyte reduction of erythrocytes are very difficult and lacking, this research took 2 years involving 246 cases of clinical research to observe the occurrence of FNHTR in clinical use, to demonstrate the effect of pre-transfusion filtration of red cells suspension on various inflammatory cytokines and their deformation by reference to related research, and to discuss the theoretical and practical significance of popularizing the filters for blood banks。Method:The preparation conditions for FFP were optimized:nine plasma preparation conditions were tested, in which plasma separation time and plasma residual were adjusted. A preparation method that could effectively decrease the leukocyte residual in plasma was found. Leukocyte residual in FFP from four blood centers was investigated. Five home-made plasma filters were used for FFP filtration. The effectiveness of leukocyte reduction for plasma quality was observed. The filtration effect of four popular platelet preparations(apheresis platelet, platelets concentration and their relative frozen platelets) was studied while observing the platelet recovery rate, leukocyte removal rate, platelet concentration rate and various platelet function index so as to choose the platelet preparation suitable for leukocyte filtration. Red cells suspension were divided into the filtration group and control group, according to whether the cells were filtered before storage. Before storage and during storage, samples were taken every week to test such cytokines as (IL-1β,IL-2,IL-6,IL-8 and TNF-α) level and erythrocytes deformation index(EI). During the 2 years of research, a total of 246 patients with more than 3 times of transfusion were chosen and 2 units of leukocyte reduced red cells suspension were transfused The patients were divided into five group according to the storage time of the transfused leukocyte reduced red cells suspension: 0d,≤7d,≤14d,≤21d and≥21d to observe the occurrence of FNHTR.Result:Prolonged plasma separation time and increased plasma residual could decrease the leukocyte residual effectively and make it reach the leukocyte reduction standard(<1×106/U). Leukocyte residual in FFP from 4 blood centers was less than 1×106/U. The home-made plasma filters did not have any impact on the quality of plasma, but their leukocyte reduction effectivenees was limited with a high plasma loss rate. The platelet recovery rate for apheresis platelet was 86.81%, which could meet the standard for platelet recovery(80%). However, the platelet recovery rate for manual concentrated platelet was only around 73%, which still could not meet the platelet recovery standard. The platelet recovery rate for two frozen platelet preparations was very low, with the platelet loss rate around 60%～70%. Before filtration, leukocyte residual in the two liquid platelet preparations was at the level of 107, while the level in manual concentrated platelets was higher (P<0.01). After filtration, the apheresis platelet met the leukocyte filtration standard(Leukocyte residual level of 105/U),whereas manually-collected plated did not meet the leukocyte reduction standard(10U leukocyte residual was 4.8×106). Filtration did not have significant impact on the function of platelet preparations stored in liquid, but the function of manual platelets was significantly lower than that of apheresis platelet. Only very low IL-1βwas detected in the two groups of red cells suspension. In the control group, blood levels of IL-2,IL-6,IL-8,TNF-αincreased gradually, suggesting that the four cytokines were accumulated in blood within the storage time. In the filtration group, IL-6, IL-8 and TNF-αall remained at a very low level during storage, and did not increase. Leukocyte filtration did not have any impact on the generation of IL-2 during storage. In the later stage of storage, EI of the filtration group was significantly higher than that of the control group. The clinical use of leukocyte reduced red cells suspension demonstrated that FNHTR occurrence was positively related to the storage time before filtration (P<0.01), and pre-storage leukocyte filtration could effectively prevent the occurrence of FNHTR.Conclusion : Compliance to standard plasma preparation procedures makes unnecessary routine leukocyte filtration for FFP . Plasma filtration could be used in some special clinical therapies, such as plasma replacement. The filtration effect of some home-made plasma filters needs to be improved and their plasma loss rate needs to be decreased. Frozen stored platelet preparations are not suitable for leukocyte filtration due to the significant platelet loss. Currently the quality of manually concentrated platelets are inferior to that of apheresis platelet,and their processes need to be updated. As their platelet recovery rate and leukocyte residual after filtration do not meet the standard for leukocyte reduced platelets, there is a need to develop quality leukocyte filters. The apheresis platelet is of good quality and could meet the leukocyte reduction standard using home-made filters, thus making it an ideal platelet preparation for leukocyte filtration. There are multiple cytokines generated and accumulated during the storage of red cells suspension, which could be prevented by leukocyte reduction to some extent. Because these cytokines could be directly related to the occurrence of FNHTR, pre-storage could decrease the occurrence of FNHTR by decreasing or preventing the accumulation of the cytokines during storage. Clinical research demonstrates that pre-storage leukocyte filtration could effectively prevent the occurrence of FNHTR. Data from both theoretical and practical research support the conclusion that red cells suspension require pre-storage leukocyte filtration. Filters for blood centers need to be used more widely in China.
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