Clinical and immunological features of platelet transfusion refractoriness in young patients with de novo acute myeloid leukemia

ABO non-identical platelet transfusions, immune platelet refractoriness and platelet support

ABO-non-identical (ABO-ni) platelets may be another risk factor for immune platelet transfusion refractoriness (i-PTR). We examined the effect of such platelets on i-PTR and subsequent platelet support through retrospective analysis of 17 322 New Zealand patients receiving ≥1 platelets. Immune PTR was defined as PTR with anti-HLA-I/HPA positivity. Univariate and multivariate analyses determined the independent risk factors for i-PTR. One hundred and eighty-eight patients (1.1%) had i-PTR and received more ABO-ni platelets than non-refractory patients (53.2% vs. 29.5%; p < 0.001). More non-O than group O patients had received ABO-ni platelets before i-PTR diagnosis (67.6% vs. 32.5%; p < 0.001). Female sex (p < 0.001), age ≤ 60 years (p = 0.004), haematology patients (p < 0.001) and ≥2 ABO-ni platelets (p < 0.001) were the independent risk factors for i-PTR. More i-PTR patients with anti-HLA-I were non-O compared to group O (90.1% vs. 75.3%; p = 0.007). More with anti-HLA-I + anti-HPA were group O than non-O (24.7% vs. 9.0%; p = 0.003). ABO-ni platelet-exposed i-PTR patients required matched platelets for longer than those receiving only ABO-i platelets (96.5 vs. 59.0 days; p = 0.02). ABO-ni platelets may be a risk factor for i-PTR with dose effect. ABO-i platelets should be considered whenever possible for at-risk patients.

A meta-analysis of risk factors associated with platelet transfusion refractoriness

BACKGROUND

Platelet transfusion refractoriness (PTR) remains an intractable issue in clinical practice, and is common in hematological patients. At present, it is believed that both immune and non-immune factors play a role. We conducted a meta-analysis of various risk factors which may contribute to PTR.

METHODS

PubMed, Embase, Cochrane library, and Web of Science were selected as research database platforms. Citations included were further assessed for quality and bias using the Newcastle-Ottawa Scale. All analyses were performed using Review Manager Version 5.4 and STATA 16.0.

RESULTS

The preliminary search revealed 1069 publications, and 17 (5929 patients in total) were ultimately included in the quantitative analysis. The following variables were associated with the occurrence of PTR: fever (OR = 2.26, 95%CI 2.00-2.55, p < 0.00001), bleeding (OR = 2.10, 95%CI 1.36-3.24, p = 0.0008), female sex (OR = 2.06, 95%CI 1.13-3.75, p = 0.02), antibiotic use (OR = 2.94, 95%CI 1.54-5.59, p = 0.001), and infection (OR = 2.19, 95%CI 1.20-4.03, p = 0.01). Antibodies involved in immune activation were a higher risk factor (OR = 4.17, 95%CI 2.36-7.36, p < 0.00001), and splenomegaly was nearly significant (OR = 1.73, 95%CI 0.97-3.07, p = 0.06).

CONCLUSIONS

We identified some important risk factors for PTR, but further research is needed to identify the many other possible elements that may contribute to or mediate PTR.

Altered Fc glycosylation of anti-HLA alloantibodies in hemato-oncological patients receiving platelet transfusions

BACKGROUND

The formation of alloantibodies directed against class I human leukocyte antigens (HLA) continues to be a clinically challenging complication after platelet transfusions, which can lead to platelet refractoriness (PR) and occurs in approximately 5%-15% of patients with chronic platelet support. Interestingly, anti-HLA IgG levels in alloimmunized patients do not seem to predict PR, suggesting functional or qualitative differences among anti-HLA IgG. The binding of these alloantibodies to donor platelets can result in rapid clearance after transfusion, presumably via FcγR-mediated phagocytosis and/or complement activation, which both are affected by the IgG-Fc glycosylation.

OBJECTIVES

To characterize the Fc glycosylation profile of anti-HLA class I antibodies formed after platelet transfusion and to investigate its effect on clinical outcome.

PATIENTS/METHODS

We screened and captured anti-HLA class I antibodies (anti-HLA A2, anti-HLA A24, and anti-HLA B7) developed after platelet transfusions in hemato-oncology patients, who were included in the PREPAReS Trial. Using liquid chromatography-mass spectrometry, we analyzed the glycosylation profiles of total and anti-HLA IgG1 developed over time. Subsequently, the glycosylation data was linked to the patients' clinical information and posttransfusion increments.

RESULTS

The glycosylation profile of anti-HLA antibodies was highly variable between patients. In general, Fc galactosylation and sialylation levels were elevated compared to total plasma IgG, which correlated negatively with the platelet count increment. Furthermore, high levels of afucosylation were observed for two patients.

CONCLUSIONS

These differences in composition of anti-HLA Fc-glycosylation profiles could potentially explain the variation in clinical severity between patients.

Phagocytosis of platelets opsonized with differently glycosylated anti-HLA hIgG1 by monocyte-derived macrophages

Immune-mediated platelet refractoriness (PR) remains a significant problem in the setting of platelet transfusion and is predominantly caused by the presence of alloantibodies directed against class I human leukocyte antigens (HLA). Opsonization of donor platelets with these alloantibodies can result in rapid clearance after transfusion via multiple mechanisms, including antibody dependent cellular phagocytosis (ADCP). Interestingly, not all alloimmunized patients develop PR to unmatched platelet transfusions, suggesting variation in HLA-specific IgG responses between patients. Previously, we observed that the glycosylation profile of anti-HLA antibodies was highly variable between PR patients, especially with respect to Fc galactosylation, sialylation and fucosylation. In the current study, we investigated the effect of different Fc glycosylation patterns, with known effects on complement deposition and FcγR binding, on phagocytosis of opsonized platelets by monocyte-derived human macrophages. We found that the phagocytosis of antibody- and complement-opsonized platelets, by monocyte derived M1 macrophages, was unaffected by these qualitative IgG-glycan differences.

Platelet-Acute Leukemia Interactions

Acute leukemia (AL) is a hematological malignancy with high morbidity and mortality that is caused by abnormal hematopoietic stem cells. AL can change the parameters, quality, and function of platelets through numerous mechanisms, resulting in bleeding and even death in AL patients. Hence, AL patients are often clinically treated using normal platelet transfusion. However, studies have found that platelets can also affect AL cells. This review discusses the changes occurring in platelet count, mean platelet volume, platelet distribution width, reticulated platelets, platelet membrane glycoprotein, platelet aggregation, and activation in AL patients, the causes of these changes, and the possible significance of these changes for patient prognosis. The effects of platelets on the proliferation and drug resistance of AL cells are also discussed.

Human Leukocyte Antigen Alloimmunization and Alloimmune Platelet Refractoriness

Despite significant advancements in the production of platelet products, storage, and transfusion, transfusion refractoriness remains a significant clinical problem, affecting up to 14% of hematological patients receiving platelet transfusions. Human leukocyte antigen (HLA) alloimmunization is a major cause of immune platelet refractoriness, and its rate can be significantly reduced by implementation of leukoreduction. Despite promising preclinical results, pathogen reduction does not reduce HLA alloimmunization. Patients with HLA alloimmune refractoriness are usually managed with HLA-selected platelet transfusions. In this review, we describe the pathophysiology of HLA alloimmunization and alloimmune refractoriness, as well as options to prevent and treat these transfusion complications. We discuss the evidence supporting these options and point out the outstanding gaps. Finally, we review the possible future directions for prevention and treatment of alloimmune refractoriness.

Clinical and immunological features of platelet transfusion refractoriness in young patients with de novo acute myeloid leukemia

Platelet transfusion is important in the prevention and treatment of bleeding in patients with acute myeloid leukemia (AML) after receiving intensive chemotherapy. However, platelet transfusion refractoriness (PTR) is an intractable clinical issue occurred in these patients. And its clinical and immunological features remain largely unknown. The potential causes and clinical features of PTR were retrospectively analyzed in 560 patients who were diagnosed as de novo AML in Tongji Hospital from June 2012 through June 2018. A high‐throughput antibody screening for the detection of human leukocyte antigen (HLA) and its serotypes was performed in 133 newly diagnosed AML patients. PTR occurred in 11.8% of the de novo AML patients. The median age for patients with PTR was 46 years (range, 15‐70). It frequently manifested in female patients and in patients with splenomegaly, M4 subtype, c‐Kit gene mutation, and rearrangements of RUNX1‐RUNX1T1 or CBFB‐MYH11, commonly referred to as core binding factor AML (CBF‐AML). Notably, CBF‐AML was independently associated with the occurrence of PTR. PTR predominantly developed in patients who had CBF‐AML (P < .001) and in patients who further had better minimal residual disease (MRD) reduction (≥3‐log) before the second consolidation chemotherapy (P = .007). HLA‐I antibodies were detected in the serum of 9.0% of AML patients and markedly enriched in patients with PTR (P < .001) and in patients with CBF‐AML (P = .018). HLA‐B was the most frequently identified serum epitope in PTR patients. Patients with CBF‐AML had higher tendency to develop HLA‐I antibodies and PTR, which depicted novel features of PTR in AML and might provide insights into its efficient managements.