Analysis of Human Platelet Antigen-1 System Alloantibodies Using Recombinant GPIIIa Fragments Coupled to Luminex Beads / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To detect platelet anti-HPA-1a and -1b antibodies using recombinant GPIIIa fragments coupled to Luminex beads.</p><p><b>METHODS</b>The sensitivity of 2 techniques, monoclonal antibody specific immobilization of platelet antigen (MAIPA) and Luminex bead assay, was compared using 12 twofold-serial dilutions (from neat to 1 in 2048) of an anti-HPA-1a WHO international standard. The specificity of Luminex assay to identify anti-HPA-1a and -1b antibodies was assessed using 8 negative or positive controls and 36 blinded samples provided by WHO Platelet Workshop.</p><p><b>RESULTS</b>The sensitivity of MAIPA and Luminex bead assay to detect anti-HPA-1a was dilution 1/64 (i.e. 1.56 IU/ml) and far more than dilution 1/2048 (i.e. 0.049 IU/mL), respectively. The Luminex bead assay could specifically identify negative and positive controls of anti-HPA-1a and -1b. All results of 36 blinded samples by Luminex assay were accordant to reference results except one sample which contained high concentration antithetical antibody and resulted in false positive of anti-HPA-1b. Cross-reactivity was also not observed with the samples containing HLA, ABO or other platelet antibodies.</p><p><b>CONCLUSION</b>The Luminex beads coupled with recombinant GPIIIa fragments can be used to detect HPA-1 system antibodies with sufficient sensitivity and specificity, that is suitable for the detection of platelet alloantibodies in clinical alloimmune thrombocytopenia.</p>

Discrimination of alleles in HLA-C*04:01:01G groups / 中国实验血液学杂志

The aim of this study was to investigate the relatively frequencies of alleles in the HLA-C*04:01:01G group and to analyze their relations with HLA-A and -B loci. DNA samples previously typed as HLA-C*04:01:01G were sequentially selected. The sequences for exon 2 to 7 of the HLA-C locus were analyzed by polymerase chain reaction sequence-based typing(PCR-SBT). The HLA-A, -B, -DRB1 and -DQB1 loci were genotyped using PCR-SBT method. The results showed that 178 samples (94.2%) and 11 samples (5.8%) were assigned as HLA-C*04:01:01 and HLA-C*04:82 respectively among 189 samples previously typed as HLA-C*04:01:01G. 72 haplotypes associated with HLA-C*04:01:01 and C*04:82 were found, in which the frequencies of 26 haplotypes were over 0.0050. HLA-C*04:01:01 was strongly related with A*02:03, A*02:07, A*11:01, A*33:03, B*13:01, B*15:01, B*15:05, B*15:27, B*40:01, B*54:01 alleles, while HLA-C*04:82 was related with B*40:01. It is concluded that HLA-C*04:01:01 and HLA-C*04:82 alleles were confirmed in the HLA-C*04:01:01G group, which should be discriminated by the routine HLA genotyping.

Establishment of method detecting CD36 expression on human platelet and its application / 中国实验血液学杂志

The individual with the deficiency of CD36 antigen on platelet displayed the risk of anti-CD36 immune reaction induced by transfusion, which is one of the reasons for platelet transfusion refractoriness (PTR). This study was purposed to detect the expression level of CD36 antigen on platelet by flow cytometry among apheresis platelet donors of Hangzhou area, and the frequency of CD36 deficiency was analyzed. Platelet-rich plasma (PRP) was separated from fresh anticoagulant whole blood by centrifugation, then the platelets were washed and adjusted to 1×10(6). The platelets were incubated with FITC-labeled CD36 and PE-labeled CD41 monoclonal antibodies, then the expression level of CD36 was detected by flow cytometry. The CD36 expression on monocytes for the samples of CD36-deficiency on the platelets was further analyzed. The results showed that 7 samples with CD36 antigen deficiency were found in 192 apheresis platelet donors. The frequency of CD36 deficiency was 3.6% and all of them were typeII deficiency. The significant difference of CD36 antigen expression was observed in the platelet donors of Hangzhou population, among them 59 individuals with low expressed CD36 antigen and 126 individuals with highly expressed CD36 antigen were found according to the geometric mean fluorescence intensity. It is concluded that the CD36 antigen deficient phenotype existed in the population, these data will provide the information for research of the CD36 antigen distribution and help to solve the platelet transfusion refractoriness.