The effect of leukocyte depletion by filtration on the quality of apheresis platelets / 中国实验血液学杂志

This study was aimed to investigate the effect of leukocyte depletion by filtration on the quality of apheresis platelets. 20 units of donor apheresis platelets were randomly selected and were preserved with agitation at 20 - 24 degrees C for 24 - 96 hours, then were filtered on polyester flatbed filters. The platelet concentration, mean platelet volume (MPV), volume of apheresis platelets, leukocyte count, pH value, lactate dehydrogenase (LDH) concentration, K(+) concentration and CD62p expression level on surface of platelet membrane, were detected before and after filtration, as well as the rate of leukocyte depletion and platelet loss were calculated. The results showed that the leukocyte count after filtration was remarkably lower than that before filtration (p < 0.001), and the rate of leukocyte depletion was 99.97%. Platelet loss was approximately 8%, and obviously lower than that of the national standard (p < 0.001). MPV, pH value, K(+) and LDH concentration were not significantly different before and after filtration. Compared with platelets before filtration, CD62p expression level after filtration slightly decreased (p > 0.05). CD62p expression on surface of platelet membrane in perfusion fluid obtained from filter plate was obviously higher than that before filtration (p < 0.05). MA of platelet after filtration slightly decreased (p > 0.05). It is concluded that leukocyte and partial activated platelets can be removed efficiently by using polyester flatbed filters, and platelet loss is very low. Filtration does not adversely affect coagulation activity of the platelets in vitro. Apheresis platelets after filtration can fulfil quality requirements to prevent infection of cytomegalovirus and HLA alloimmunization.

Establishment of genotyping method for fetal ABO group from pregnant maternal peripheral blood / 中国实验血液学杂志

This study was aimed to establish a genotyping method to detect ABO group gene of fetus from peripheral blood of pregnant women for prenatal diagnosis of hemolytic disease of newborn (HDN) resulting from ABO blood group incompatibility. 4 pairs of primers were designed according to ABO blood group gene DNA and mRNA sequences. 20 plasma DNA samples from healthy donors were extracted and amplified to explore the best conditions for plasma DNA extraction and PCR amplification. The O group plasma DNA was mixed with A group or B group plasmas by the ratios of 1:1, 2:1, 4:1, 8:1, 10:1, 20:1, 40:1, 100:1 to simulate the status of mixed ABO gene from pregnant maternal blood and to establish the mixed blood group ABO genotyping technology. The pregnant maternal blood samples with more than 30 weeks of gestation were selected for detecting the fetal ABO blood group genotype. The blood samples should be taken as possible as after birth for identification of ABO blood group and evaluation of sensitivity and accuracy of fetal ABO blood group genotyping technology through peripheral blood of pregnant women. The results indicated that the minimal amount of template DNA from single blood plasma for accuracy identification was at least about 0.625 ng, the DNA amount extracted from 500 microl of plasma could meet the requirement for PCR amplification. When the proportion of O group plasma DNA in mixed plasma DNA was <or=10, the non-O group gene could be accurately detected. Among 14 peripheral blood samples from O-group pregnant women, the non-O group gene was amplified in 9 samples; the non-O group gene was not amplified in 5 samples. The identification of peripheral blood ABO group for 5 newborns using serologic method showed that the A group 3 cases, B group 2 cases, O group 1 case, which consisted with genotyping results with consistent rate 100%. It is concluded that in middle and late pregnancy the fetal ABO group gene can be detected accurately by means of established fetal ABO group gene extraction and typing technology, that provides some guidances for the prenatal diagnosis and prevention of HDN.

Application of thrombelastography in evaluation of platelet function during storage / 中国实验血液学杂志

This study was aimed to explore changes of platelet function in vitro during storage by thrombelastography (TEG). 12 units plateletpheresis were randomly selected and stored at 20 to 24 degrees C with agitation. Thrombelastography variable parameters R, K values and maximal amplitude (MA) were measured on 1, 2, 3, 4, 5 days of platelet storage. Platelet concentration, mean platelet volume (MPV), hypotonic shock response (HSR), CD62p expression and CD62p reexpression on platelet surface were detected at the same time. Changes of platelet function in virto were systematically evaluated by above-mentioned indexes. The results showed that MPV augmented slightly with prolongation of preserved time (p > 0.05), and CD62p expression on platelet surface increased remarkably (p < 0.01), while CD62p reexpression decreased gradually (p < 0.01). There were no significant differences in HSR level of platelets during storage (p > 0.05). R value increased with prolongation of preserved time (p < 0.01). There were no obvious changes on K value and alpha Angle during storage (p > 0.05). There were no obvious changes in MA from 1 to 4 days, and MA decreased slightly on day 5 (p < 0.05). It is concluded that there was no significant change in MA and HSR which reflects comprehensive coagulation of platelets during storage. Platelets on the end of storage have excellent function of hemostasis; Thrombelastography parameter MA value can be used as a valuable indicator for evaluation of platelet function in vitro during storage.