Can we "terminate" alloimmune platelet transfusion refractoriness?

Group-Based Trajectory Modeling of Platelet in Patients with Aplastic Anemia: A Study Based on the MIMIC Database

Background

Platelets are the main components supporting coagulation and hemostasis. Nevertheless, no sufficient research has been done on how variations in platelet counts during hospital stays affect aplastic anemia (AA) patients' prognoses.

Objective

This study proposes to evaluate the association between alterations in platelet levels and illness risk in patients with AA using group-based trajectory modeling (GBTM).

Methods

GBTM was used to group AA patients based on changes in platelet levels. Cox regression models were used to evaluate the relationship between platelet levels and patients' 30-day survival status. Kaplan-Meier (K-M) survival curve analysis was used to assess the impact of platelet transfusion on survival among different trajectory groups of patients.

Results

Three trajectory patterns were recognized by GBTM: Class 1, Class 2, and Class 3. Even after controlling for confounding variables, the Cox risk estimates showed that AA patients had a higher chance of surviving in Class 1 (OR>1, P<0.05). Class 2 patients had the greatest survival, according to K-M (Log-rank P<0.001). According to landmark research, Class 1 patients' survival was not improved by platelet transfusion.

Conclusion

Patients with AA who had increasing platelet trajectories during their hospital stay had a higher 30-day survival rate; hence, patients with low platelet counts might not be good candidates for platelet transfusion treatment.

The clinical characteristics of patients with acute leukemia or stem cell transplantation exhibiting immune based platelet refractoriness

BACKGROUND

To investigate the related factors influencing immune platelet transfusion refractoriness (PTR) in acute leukemia (AL) from induction to consolidation and compare management for immune PTR, so as to improve the Platelet increment in AL.

METHODS

The primary analysis included 890 patients with AL, 225 of whom were the immune PTR (25 %).They are patients in our center from induction to consolidation or transplantation in the past 10 years. Flow cytometry, karyotype characteristics and other basic information were compared between the immune PTR vs control (no-PTR) groups. We analyzed the treatment outcomes of immune PTR including matched platelets, intravenous immunoglobulin (IVIG), increasing apheresis platelet does.

RESULTS

Immune PTR is more likely to occur in patients with poor prognosis in acute lymphoblastic leukemia (ALL) (P = 0.01).There is a relation between NPM1 mutation and occurrence of immune PTR (P = 0.029).The incidence of PTR at 35-59Y was higher than that at <35Y(OR = 0.68, 95 % CI = 0.48-0.96) and ≥60Y(OR = 0.49,95 % CI = 0.28-0.83), and the difference was statistically significant(P = 0.03, P = 0.01).The Platelet increment with 1 unit (u) was 47.12 %, 2 u increased to 71.14 %, and the matched 2 u (75.11 %) had the best effect. IVIG improved the Platelet increment, but there was no difference between 0.4 g/kg IVIG and 1 g/kg IVIG. Immune PTR is more likely to occur in the ages of 35-60 years.

CONCLUSION

There are specific AL patient characteristics which predispose to the phenomenon of immune based PTR. Meanwhile, increasing the IVIG dose could not improve Platelet increment obviously.

Novel method for simultaneously detecting HPA and HLA antibodies using Luminex microbeads

Background

Alloantibodies against human platelet antigens (HPAs) and human leukocyte antigen (HLA) are implicated in several immune-mediated platelet disorders. Detection of these antibodies is crucial in the diagnosis and management of these disorders. The aim of this study was to establish a novel method to simultaneously detect HPA-1, HPA-2, HPA-3, HPA-5 and HLA antibodies with Luminex microbeads technology.

Methods

Monoclonal antibodies specific for platelet glycoproteins and HLA class I molecules were separately coupled to the Luminex microbeads. We validated specificity of the Luminex platform using the following antibodies: anti-HPA-1a, anti-HPA-2b, anti-HPA-3a, anti-HPA-5a, and anti-HLA positive samples. Sensitivity was evaluated by a serial dilution (from neat to 1/1024) using the following antibodies: anti-HPA-1a, anti-HPA-3a standard sera, and anti-HPA-5a positive serum. Serum samples were collected from 36 neonatal alloimmune thrombocytopenia (NAIT) patients suspected of having HPA or HLA antibodies and 8 samples from ISBT platelet workshop were tested using the Luminex assay.

Results

The Luminex assay detected all antibodies tested from the known samples. The sensitivities of the Luminex assay detecting anti-HPA-1a, anti-HPA-3a, and anti-HPA-5a were 1:512, 1:64, and 1:128, respectively. The sensitivity of Luminex assay was higher than monoclonal antibody immobilization of platelet antigen method (MAIPA). No cross-reactivity was observed in the samples containing multi-platelet antibodies or mixture antibodies against HPA and HLA. The results of 44 samples with platelet disorders were consistent with those of the same samples processed with the MAIPA assay.

Conclusion

Luminex microbeads coupled with monoclonal antibodies could be successfully used to detect HPA and HLA antibodies simultaneously, especially with high sensitivity in detecting HPA antibodies.

Routine Screening Method for Microparticles in Platelet Transfusions

Platelet inventory management based on screening microparticle content in platelet concentrates is a new quality improvement initiative for hospital blood banks. Cells fragment off microparticles (MP) when they are stressed. Blood and blood components may contain cellular fragments from a variety of cells, most notably from activated platelets. When performing their roles as innate immune cells and major players in coagulation and hemostasis, platelets change shape and generate microparticles. With dynamic light scattering (DLS)-based microparticle detection, it is possible to differentiate activated (high microparticle) from non-activated (low microparticle) platelets in transfusions, and optimize the use of this scarce blood product. Previous research suggests that providing non-activated platelets for prophylactic use in hematology-oncology patients could reduce their risk of becoming refractory and improve patient care. The goal of this screening method is to routinely differentiate activated from non-activated platelets. The method described here outlines the steps to be performed for routine platelet inventory management in a hospital blood bank: obtaining a sample from a platelet transfusion, loading the sample into the capillary for DLS measurement, performing the DLS test to identify microparticles, and using the reported microparticle content to identify activated platelets.

Simultaneous genotyping of human platelet alloantigen-1 to 28bw systems by multiplex polymerase chain reaction sequence-based typing

BACKGROUND AND OBJECTIVES

Human platelet alloantigen (HPA) genotyping is important for the diagnosis and prevention the alloimmune platelet disorders. In this study, a simultaneous genotyping method for HPA-1 to -28bw systems was established using multiplex PCR-SBT and the frequencies of genotypes and alleles of HPA-1 to -28bw systems in the Zhejiang Han population were analysed.

MATERIALS AND METHODS

The specific primers were designed according to the nucleotide sequences of HPA-1 to 28bw systems which are located in ITGB3, GP1BA, ITGA2B, ITGA2, GP1BB and CD109, respectively. The multiplex PCR amplification systems were used, and then, the amplicons were purified and sequenced. A total of 335 healthy volunteer blood donors were detected.

RESULTS

The genotypes of ten reference samples from Platelet Immunology Workshop of ISBT were in concordance with the known genotypes. Among the 28 HPA systems, HPA a and b alleles were found in HPA-1 to 6w, HPA-15 and HPA-21w systems in the Chinese Han population, while only HPA aa genotype was detected in the other HPA systems. The frequencies of HPA-1a and HPA-1b were 0·993 and 0·007, with 0·943 and 0·057 for HPA-2a and HPA-2b, 0·527 and 0·473 for HPA-3a and HPA-3b, 0·997 and 0·003 for HPA-4a and HPA-4b, 0·991 and 0·009 for HPA-5a and HPA-5b, 0·980 and 0·020 for HPA-6wa and HPA-6wb, 0·508 and 0·492 for HPA-15a and HPA-15b and 0·994 and 0·006 for HPA-21wa and HPA-21wb.

CONCLUSIONS

One multiplex PCR-SBT method for HPAs was established and the data of the study could help to prevent and treat for alloimmune thrombocytopenia.