Transfusion-induced bone marrow transplant rejection due to minor histocompatibility antigens

Platelet transfusion in adults: An update

Many patients worldwide receive platelet components (PCs) through the transfusion of diverse types of blood components. PC transfusions are essential for the treatment of central thrombocytopenia of diverse causes, and such treatment is beneficial in patients at risk of severe bleeding. PC transfusions account for almost 10% of all the blood components supplied by blood services, but they are associated with about 3.25 times as many severe reactions (attributable to transfusion) than red blood cell transfusions after stringent in-process leukoreduction to less than 10⁶ residual cells per blood component. PCs are not homogeneous, due to the considerable differences between donors. Furthermore, the modes of PC collection and preparation, the safety precautions taken to limit either the most common (allergic-type reactions and febrile non-hemolytic reactions) or the most severe (bacterial contamination, pulmonary lesions) adverse reactions, and storage and conservation methods can all result in so-called PC "storage lesions". Some storage lesions affect PC quality, with implications for patient outcome. Good transfusion practices should result in higher levels of platelet recovery and efficacy, and lower complication rates. These practices include a matching of tissue ABH antigens whenever possible, and of platelet HLA (and, to a lesser extent, HPA) antigens in immunization situations. This review provides an overview of all the available information relating to platelet transfusion, from donor and donation to bedside transfusion, and considers the impact of the measures applied to increase transfusion efficacy while improving safety and preventing transfusion inefficacy and refractoriness. It also considers alternatives to platelet component (PC) transfusion.

Analysis of T-Cell Receptor Repertoire in Transplantation: Fingerprint of T Cell-mediated Alloresponse

T cells play a key role in determining allograft function by mediating allogeneic immune responses to cause rejection, and recent work pointed their role in mediating tolerance in transplantation. The unique T-cell receptor (TCR) expressed on the surface of each T cell determines the antigen specificity of the cell and can be the specific fingerprint for identifying and monitoring. Next-generation sequencing (NGS) techniques provide powerful tools for deep and high-throughput TCR profiling, and facilitate to depict the entire T cell repertoire profile and trace antigen-specific T cells in circulation and local tissues. Tailing T cell transcriptomes and TCR sequences at the single cell level provides a full landscape of alloreactive T-cell clones development and biofunction in alloresponse. Here, we review the recent advances in TCR sequencing techniques and computational tools, as well as the recent discovery in overall TCR profile and antigen-specific T cells tracking in transplantation. We further discuss the challenges and potential of using TCR sequencing-based assays to profile alloreactive TCR repertoire as the fingerprint for immune monitoring and prediction of rejection and tolerance.

High B-cell activating factor levels in multi-transfused thalassemia patients

OBJECTIVES

To assess the associations between B-cell activating factor (BAFF) and alloimmunisation in multi-transfused thalassemia.

BACKGROUND

Red blood cell (RBC) alloimmunisation is a complication of multi-transfused thalassemia. BAFF is promoting B cells that produce alloantibodies.

METHODS/MATERIALS

Multi-transfused thalassemia, 15 years or older, were recruited in the cohort study. Alloantibodies and BAFF levels were analysed.

RESULTS

Of 114 patients, the overall prevalence of RBC alloimmunisation was 29.8%. The most common alloantibodies were anti-E, anti-Mi^a and anti-c. BAFF levels were different among the three groups; the patients with baseline alloantibodies (median ± interquartile range 1251 ± 474 pg/ml), without alloantibodies (1098 ± 453) and healthy controls (719 ± 306), p < 0.001. The BAFF level was elevated in the >25 years old patients (vs. the <25, p = 0.011) and the buffy-coat-reduced blood recipients (vs. the pre-storage leukocyte-depletion, p = 0.005). Absolute lymphocyte count was higher in the patients without baseline alloantibodies (vs. with baseline alloantibodies, p = 0.049) and the splenectomised patients (vs. the non-splenectomised patients, p < 0.001). Of the 72 patients without baseline antibodies, four who developed new antibodies showed no statistically different BAFF levels compared with those without new antibodies after 40-month follow-up (1296 ± 734 vs. 1062 ± 460, p = 0.491). In multivariate analysis, BAFF to absolute lymphocyte ratio was independently associated with RBC alloimmunisation (odds ratio 3.07, 95% confidence interval 1.124-8.369, p = 0.029).

CONCLUSION

B-cell activating factor (BAFF) levels were elevated in multi-transfused thalassemia and the BAFF to absolute lymphocyte ratio was associated with red blood cell (RBC) alloimmunisation.

Patterns and correlates of preserved humoral immunity to vaccines in children following allogeneic hematopoietic stem cell transplantation

Data on preservation of vaccine immunity following allogeneic HSCT in children is limited. We investigated vaccine titers and sought correlations with patient characteristics in this study. Twenty-eight cases were retrospectively analyzed. Antibody concentrations against hepatitis A, hepatitis B, 3 poliovirus serotypes, tetanus, diphtheria, measles, mumps, rubella, varicella, and 13 pneumococcus serotypes were measured as part of planned monitoring following HSCT. Protective antibody levels were found for hepatitis A in 79% of the recipients, measles in 54%, all poliovirus serotypes in 50%, tetanus in 50%, rubella in 50%, varicella in 46%, hepatitis B in 46%, mumps in 43%, diphtheria in 29%, and ≥7/13 pneumococcus serotypes in 46%; lowest level observed for diphtheria and highest for hepatitis A prior to starting post-HSCT immunizations. In univariate analysis, patients with non-malignant diseases (P = .03) and without GvHD (P = .04) had more protective titers. A significant positive association was found among vaccine titers against the microorganisms or the serotypes of the same microorganism, which were administered together in the same product, including polio serotypes, diphtheria and tetanus, mumps, measles, and rubella. Higher degrees of sero-positivity are likely to be due to lack of prior chemotherapy in non-malignant disease cases and lesser immunosuppression in patients without GvHD. Monitoring long-term vaccine titers and administering vaccines accordingly could be evaluated for post-HSCT re-immunization practice.

Primary Immunodeficiency and Thrombocytopenia

Primary immunodeficiency (PID) or Inborn errors of immunity (IEI) refers to a heterogeneous group of disorders characterized by immune system impairment. Although patients with IEI manifest highly variable symptoms, the most common clinical manifestations are recurrent infections, autoimmunity and malignancies. Some patients present hematological abnormality including thrombocytopenia due to different pathogenic mechanisms. This review focuses on primary and secondary thrombocytopenia as a complication, which can occur in IEI. Based on the International Union of Immunological Societies phenotypic classification for IEI, the several innate and adaptive immunodeficiency disorders can lead to thrombocytopenia. This review, for the first time, describes manifestation, mechanism and therapeutic modalities for thrombocytopenia in different classes of IEI.

Toward dual hematopoietic stem-cell transplantation and solid-organ transplantation for sickle-cell disease

Sickle-cell disease (SCD) leads to recurrent vaso-occlusive crises, chronic end-organ damage, and resultant physical, psychological, and social disabilities. Although hematopoietic stem-cell transplantation (HSCT) is potentially curative for SCD, this procedure is associated with well-recognized morbidity and mortality and thus is ideally offered only to patients at high risk of significant complications. However, it is difficult to identify patients at high risk before significant complications have occurred, and once patients experience significant organ damage, they are considered poor candidates for HSCT. In turn, patients who have experienced long-term organ toxicity from SCD such as renal or liver failure may be candidates for solid-organ transplantation (SOT); however, the transplanted organs are at risk of damage by the original disease. Thus, dual HSCT and organ transplantation could simultaneously replace the failing organ and eliminate the underlying disease process. Advances in HSCT conditioning such as reduced-intensity regimens and alternative donor selection may expand both the feasibility of and potential donor pool for transplantation. This review summarizes the current state of HSCT and organ transplantation in SCD and discusses future directions and the clinical feasibility of dual HSCT/SOT.

Mechanisms of red blood cell transfusion-related immunomodulation

Red blood cell (RBC) transfusion is common in critically ill, postsurgical, and posttrauma patients in whom both systemic inflammation and immune suppression are associated with adverse outcomes. RBC products contain a multitude of immunomodulatory mediators that interact with and alter immune cell function. These interactions can lead to both proinflammatory and immunosuppressive effects. Defining clinical outcomes related to immunomodulatory effects of RBCs in transfused patients remains a challenge, likely due to complex interactions between individual blood product characteristics and patient-specific risk factors. Unpacking these complexities requires an in-depth understanding of the mechanisms of immunomodulatory effects of RBC products. In this review, we outline and classify potential mediators of RBC transfusion-related immunomodulation and provide suggestions for future research directions.

[Study on the expression of T, B lymphocyte antigen and platelet antibodies in patients with platelet transfusion refractoriness]

目的

探讨T、B淋巴细胞，血小板膜糖蛋白和血小板抗体在血小板输注无效中作用。

方法

选择41例临床确诊血小板输注无效患者为研究对象，以27例血小板输注有效患者为对照组，采用流式细胞术检测两组患者外周血细胞毒性T淋巴细胞（CD3 ⁺CD4⁻CD8⁺）、辅助性T淋巴细胞（CD3 ⁺ CD4⁺CD8⁻）、B淋巴细胞（CD19⁺）比例和血小板膜糖蛋白CD41а、CD61的表达，采用固相凝集法检测两组患者血清中的血小板抗体。

结果

与对照组比较，血小板输注无效组患者：①辅助性T细胞比例明显下降（36.60%对48.53%），细胞毒性T细胞比例显著增高（53.26%对44.02%），二者比值下降（0.85对1.31），差异均有统计学意义（P值均<0.05）；②B淋巴细胞比例差异无统计学意义（3.02%对2.85%，P=0.901）；③CD41а阳性细胞率[（88.10±12.75）%对（51.69±24.45）%，P=0.001]和CD61阳性细胞率[（88.36±12.31）%对（51.83±24.48）%，P<0.001]均显著升高；④血小板抗体阳性率显著增高（85.37%对14.82%，P<0.05）。

结论

细胞毒性T淋巴细胞的激活、辅助性T细胞的抑制、血小板膜糖蛋白CD41а和CD61的表达以及血小板抗体的产生均在血小板输注无效的发生过程中发挥重要作用。

Use of Alefacept for Preconditioning in Multiply Transfused Pediatric Patients with Nonmalignant Diseases

Transfusion-related alloimmunization is a potent barrier to the engraftment of allogeneic hematopoietic stem cells in patients with nonmalignant diseases (NMDs). Memory T cells, which drive alloimmunization, are relatively resistant to commonly used conditioning agents. Alefacept, a recombinant leukocyte function antigen-3/IgG1 fusion protein, targets CD2 and selectively depletes memory versus naive T cells. Three multiply transfused pediatric patients with NMD received a short course of high-dose i.v. alefacept (.25 mg/kg/dose on days -40 and -9 and .5 mg/kg/dose on days -33, -26, -19, and -12) before undergoing unrelated allogeneic transplant in the setting of reduced-intensity pretransplant conditioning and calcineurin inhibitor-based post-transplant graft-versus-host disease (GVHD) prophylaxis. Alefacept infusions were well tolerated in all patients. Peripheral blood flow cytometry was performed at baseline and during and after alefacept treatment. As expected, after the 5 weekly alefacept doses, each patient demonstrated selective loss of CD2(hi)/CCR7(-)/CD45RA(-) effector memory (Tem) and CD2(hi)/CCR7(+)/CD45RA(-) central memory (Tcm) CD4(+) and CD8(+) T cells with relative preservation of the CD2(lo) Tem and Tcm subpopulations. In addition, depletion of CD2(+) natural killer (NK) cells also occurred. Neutrophil recovery was rapid, and all 3 patients had 100% sorted (CD3/CD33) peripheral blood donor chimerism by day +100. Immune reconstitution (by absolute neutrophil, monocyte, and lymphocyte counts) was comparable with a cohort of historical control patients. All 3 patients developed GVHD but are all now off immune suppression and >2 years post-transplant with stable full-donor engraftment. These results suggest that alefacept at higher dosing can deplete both memory T cells and NK cells and that incorporating CD2-targeted depletion into a reduced-intensity transplant regimen is feasible and safe in heavily transfused patients.

Red blood cell transfusions are associated with HLA class I but not H-Y alloantibodies in children with sickle cell disease

Blood transfusions can induce alloantibodies to antigens on red blood cells (RBCs), white blood cells and platelets, with these alloantibodies affecting transfusion and transplantation. While transfusion-related alloimmunization against RBC antigens and human leucocyte antigens (HLA) have been studied, transfusion-related alloimmunization to minor histocompatibility antigens (mHA), such as H-Y antigens, has not been clinically characterized. We conducted a cross-sectional study of 114 children with sickle cell disease (SCD) and tested for antibodies to 5 H-Y antigens and to HLA class I and class II. Few patients had H-Y antibodies, with no significant differences in the prevalence of any H-Y antibody observed among transfused females (7%), transfused males (6%) and never transfused females (4%). In contrast, HLA class I, but not HLA class II, antibodies were more prevalent among transfused than never transfused patients (class I: 33% vs. 13%, P = 0·046; class II: 7% vs. 8%, P = 0·67). Among transfused patients, RBC alloantibody history but not amount of transfusion exposure was associated with a high (>25%) HLA class I panel reactive antibody (Odds ratio 6·8, 95% confidence interval 2·1-22·3). These results are consistent with immunological responder and non-responder phenotypes, wherein a subset of patients with SCD may be at higher risk for transfusion-related alloimmunization.

Strategies to inhibit alloantibody production in alloprimed murine recipients of hematopoietic stem cell grafts

Alloantibody, not primed T cells, is the major barrier to bone marrow (BM) engraftment in allosensitized mice. We have shown that a single intravenous injection of donor splenocytes, to mimic a blood transfusion, results in high, sustained levels of serum alloantibody sufficient to eliminate donor BM within 3 h, resulting in uniform mortality in lethally irradiated allogeneic recipients. Current studies focused preventing and treating allopriming. Blockade of B cell survival signals with mTACI-Ig pre- and postpriming was ineffective, as was the B cell but not plasma cell depleting anti-CD20 mAb. Germinal center formation inhibition by lymphotoxin-beta receptor-Ig (LβR-Ig) diminished allosensitization, although conditional Prmd1 (Blimp-1) deletion in CD19+ cells was highly effective. By combining anti-CD20 mAb to reduce B cells and LTβR-Ig to diminish the frequency of B cells that could form germinal centers pre- and postpriming, allosensitization was precluded, permitting long-term survival in T- and NK-depleted, irradiated allogeneic recipients, whereas combined therapy postpriming alone was ineffective. As evidence of the critical role of B cells, the proteosomal inhibitor, bortezomib, given unencapsulated or encapsulated, proved ineffective in influencing allosensitization. These data extend our understanding of allopriming and provide a potential therapy for patients at risk for allosensitization and BM graft rejection.