Immune regulation in chronically transfused allo-antibody responder and nonresponder patients with sickle cell disease and ß-thalassemia major.

Red blood cell alloimmunization is a major complication of transfusion therapy. Host immune markers that can predict antibody responders remain poorly described. As regulatory T cells (Tregs) play a role in alloimmunization in mouse models, we analyzed the Treg compartment of a cohort of chronically transfused patients with sickle cell disease (SCD, n = 22) and ß-thalassemia major (n = 8) with and without alloantibodies. We found reduced Treg activity in alloantibody responders compared with nonresponders as seen in mice. Higher circulating anti-inflammatory IL-10 levels and lower IFN-γ levels were detected in non-alloimmunized SCD patients. Stimulated sorted CD4+ cells from half of the alloimmunized patients had increased frequency of IL-4 expression compared with nonresponders, indicating a skewed T helper (Th) 2 humoral immune response in a subgroup of antibody responders. All patients had increased Th17 responses, suggesting an underlying inflammatory state. Although small, our study indicates an altered immunoregulatory state in alloantibody responders which may help future identification of potential molecular risk factors for alloimmunization.

Differentiation of allogeneic mesenchymal stem cells induces immunogenicity and limits their long-term benefits for myocardial repair.

BACKGROUND: Cardiac cell therapy for older patients who experience a myocardial infarction may require highly regenerative cells from young, healthy (allogeneic) donors. Bone marrow mesenchymal stem cells (MSCs) are currently under clinical investigation because they can induce cardiac repair and may also be immunoprivileged (suitable for allogeneic applications). However, it is unclear whether allogeneic MSCs retain their immunoprivilege or functional efficacy late after myocardial implantation. We evaluated the effects of MSC differentiation on the immune characteristics of cells in vitro and in vivo and monitored cardiac function for 6 months after post-myocardial infarction MSC therapy. METHODS AND RESULTS: In the in vitro experiments, inducing MSCs to acquire myogenic, endothelial, or smooth muscle characteristics (via 5-azacytidine or cytokine treatment) increased major histocompatibility complex-Ia and -II (immunogenic) expression and reduced major histocompatibility complex-Ib (immunosuppressive) expression, in association with increased cytotoxicity in coculture with allogeneic leukocytes. In the in vivo experiments, we implanted allogeneic or syngeneic MSCs into infarcted rat myocardia. We measured cell differentiation and survival (immunohistochemistry, real-time polymerase chain reaction) and cardiac function (echocardiography, pressure-volume catheter) for 6 months. MSCs (versus media) significantly improved ventricular function for at least 3 months after implantation. Allogeneic (but not syngeneic) cells were eliminated from the heart by 5 weeks after implantation, and their functional benefits were lost within 5 months. CONCLUSIONS: The long-term ability of allogeneic MSCs to preserve function in the infarcted heart is limited by a biphasic immune response whereby they transition from an immunoprivileged to an immunogenic state after differentiation, which is associated with an alteration in major histocompatibility complex-immune antigen profile.

Delayed hemolytic transfusion reaction due to anti-Fyb caused by a primary immune response: a case study and a review of the literature.

Delayed hemolytic transfusion reactions (DHTRs) usually occur between 3 and 14 days posttransfusion as a result of a secondary immune response, with a drop in Hb level, fever, jaundice, or hemoglobinuria. DHTRs caused by a primary immune response are particularly rare events, and only a few reports have been known. In this report, we describe an unusual case of a DHTR caused by anti-Fyb in a 42-year-old man, who had no prior history of transfusion. Although it seems to be a rare phenomenon, we suggest that DHTRs by a primary immune response may be considered even in the case of the patient who had typical evidence of hemolysis but who had no previous transfusion history.

Allograft rejection by primed/memory CD8+ T cells is CD154 blockade resistant: therapeutic implications for sensitized transplant recipients.

We have shown that CD8(+) CTLs are the key mediators of accelerated rejection, and that CD8(+) T cells represent the prime targets of CD154 blockade in sensitized mouse recipients of cardiac allografts. However, the current protocols require CD154 blockade at the time of sensitization, whereas delayed treatment fails to affect graft rejection in sensitized recipients. To elucidate the mechanisms of costimulation blockade-resistant rejection and to improve the efficacy of CD154-targeted therapy, we found that alloreactive CD8(+) T cells were activated despite the CD154 blockade in sensitized hosts. Comparative CD8 T cell activation study in naive vs primed hosts has shown that although both naive and primed/memory CD8(+) T cells relied on the CD28 costimulation for their activation, only naive, not primed/memory, CD8(+) T cells depend on CD154 signaling to differentiate into CTL effector cells. Adjunctive therapy was designed accordingly to deplete primed/memory CD8(+) T cells before the CD154 blockade. Indeed, unlike anti-CD154 monotherapy, transient depletion of CD8(+) T cells around the time of cardiac engraftment significantly improved the efficacy of delayed CD154 blockade in sensitized hosts. Hence, this report provides evidence for 1) differential requirement of CD154 costimulation signals for naive vs primed/memory CD8(+) T cells, and 2) successful treatment of clinically relevant sensitized recipients to achieve stable long term graft acceptance.

HLA class II antibodies in transfusion-related acute lung injury.

BACKGROUND: Transfusion-related acute lung injury (TRALI) is a serious, sometimes fatal, complication of transfusion. Granulocyte and HLA class I antibodies present in blood donors have been associated with TRALI. HLA class II antibodies have recently been described in a few cases of TRALI. STUDY DESIGN AND METHODS: Donors involved in TRALI reactions reported to a blood center over an 18-month period were tested for HLA class I and II antibodies as well as granulocyte antibodies, if HLA antibodies were not identified. RESULTS: HLA class II antibodies were identified, in at least one donor, in 7 (64%) of 11 cases of TRALI. HLA class I antibodies were identified in combination with HLA class II antibodies in 5 of these 7 cases. HLA class I antibodies were exclusively identified in 2 cases. Granulocyte antibodies were identified in 1 case, and no antibodies were identified in another. CONCLUSION: In addition to HLA class I antibodies, HLA class II antibodies are associated with TRALI. Testing of donors for HLA class II antibodies as well as HLA class I and granulocyte antibodies is recommended as part of the investigation of suspected cases of TRALI.

Transfusion-related acute lung injury associated with interdonor incompatibility for the neutrophil-specific antigen HNA-1a.

BACKGROUND AND OBJECTIVES: A patient transfused with two pooled platelet concentrates became breathless. Bilateral infiltrates were seen on chest X-ray. A diagnosis of transfusion-related acute lung injury (TRALI) was made. The patient received 100% oxygen and recovered after 5 days. MATERIALS AND METHODS: Antibody screening, cross-matching for granulocyte and lymphocyte antibodies and typing for granulocyte antigens was undertaken. RESULTS: The patient typed as HNA-1b/HNA-1b. Granulocyte and lymphocyte antibodies were not detected in the patient's serum or in any of the donor sera by cross-match. In antibody screening against typed panel granulocytes, complement-fixing anti-HNA-1a IgM antibodies were detected in the serum of one female donor. Two of the other donors who contributed to the pooled platelet concentrate containing the HNA-1a IgM antibodies typed as HNA-1a/HNA-1b. CONCLUSION: Anti-HNA-1a IgM antibodies may have formed immune complexes with white cell fragments or soluble FcgammaRIII from HNA-1a+ donors in the pooled platelet concentrate and initiated TRALI.

Red blood cell polyagglutination: clinical aspects.

Polyagglutination is the term applied to red blood cells (RBCs) that are agglutinated by almost all samples of human sera from adults but not by autologous serum or sera of newborns. The polyagglutinable state may be transient or persistent. Transient polyagglutinability results from the exposure of normally cryptic antigens by bacterial enzymatic activity during the course of an infectious process. RBCs are polyagglutinable because most sera from adults contain agglutinins for the exposed antigens. This type of polyagglutination can often be reproduced in vitro with bacterial culture fluids or isolated enzymes. Persistent polyagglutination may be a consequence of somatic mutation leading to a cellular lineage characterized by an enzyme deficiency that results in exposure of a normally cryptic antigen, Tn. Most human sera contain anti-Tn. Tn polyagglutination is regularly accompanied by leukopenia and thrombocytopenia and has been associated with leukemia. Other forms of persistent polyagglutination are due to the inheritance of rare blood groups or are associated with a hematologic dyscrasia.

One antigen mismatched related donor bone marrow transplant in a patient with acute lymphoblastic leukaemia and beta-thalassaemia major: potential cure of both marrow disorders.

We report a case of a 34-year-old man with T-ALL and beta-thalassaemia major who underwent a one antigen mismatched related donor bone marrow transplant. Five months post transplant chimeric studies revealed full donor haemopoiesis and the patient remains leukaemia and thalassaemia free at 12 months post transplant. Cumulative risk factors contributing to the increased transplant-related mortality in patients with two different marrow disorders are discussed.

Major surgery for a gastric cancer in a haemophilic with high inhibitor titre successfully performed by the use of recombinant FVIIa.

A total gastrectomy with omentectomy and resection of the distal oesophagus in a 69-year-old haemophilia A patient with high inhibitor of 128 Bethesda units is described. Surgery was successfully performed after infusion of 112 microg kg-1 bw of recombinant FVIIa. Ninety-two microg kg-1 were given thereafter at time intervals of 2 h until 12 h, then every 3 h until 24 h, and every 4 h until 48 h after surgery. Doses were gradually reduced in the following days and finally discontinued on day 28 after surgery. The complete treatment schedule required the administration of a total of 708 mg of recombinant FVIIa. Using this approach, we observed normal haemostasis, and there were no signs of excessive postoperative bleeding or wound haematoma. No clinical side-effects or evidence of systemic activation of coagulation occurred during the treatment. As judged from the clinical course of this major surgery, recombinant FVIIa appears to be highly efficacious and safe and should be used as first line treatment in high titre inhibitor patients with cross-reactivity to porcine factor VIII, undergoing surgery.

Noninfectious complications of blood transfusion.

The noninfectious complications of blood transfusion consist of a diverse group of immune-mediated transfusion reactions that range from immediate life-threatening to subclinical reactions. Each reaction involves the recognition and interaction of the both the humoral and cellular immune systems. In the past, many of the noninfectious complications of transfusion were attributed solely to antigen-antibody interactions. Today, an emerging body of evidence suggests that cytokines and cytokine inhibitors play a central role in the pathophysiology of immune-mediated transfusion reactions and account for the broad diversity of clinical presentations.

Immunosuppressive effects of allogeneic blood transfusions: implications for the patient with a malignancy.

A considerable amount of information has accumulated over the past decade indicating that the transfusion of allogeneic blood products may be associated with adverse effects to the recipient. These include the development of transfusion reactions, TA-GVHD, HLA-alloimmunization, and immunomodulatory effects. The latter might be beneficial for recipients of kidney allografts, in reducing the relapse rate in patients with Crohn's disease, and in ameliorating the rate of recurrence of spontaneous abortion in affected patients; however, the immunosuppressive effects associated with perioperative ABT might adversely affect overall prognosis in patients with a malignancy who undergo curative cancer surgery. In addition, ABT has been shown to be associated with an increased risk for postoperative bacterial infections. The ABT-induced immunomodulatory effects appear to be mediated immunologically by transfused allogeneic passenger leukocytes. The 3 log10 leukocyte reduction of cellular blood products, provided by the currently available commercial leukocyte filters, has been shown to minimize the occurrence of some of the ABT-associated deleterious effects; however, the actual clinical efficacy of leukodepletion has not yet been established, because the available data are largely from retrospective or uncontrolled clinical studies. Properly designed prospective clinical trials are essential to establish optimal conditions for the preparation of blood components destined for clinical use.

Cytokine dysregulation as a mechanism of graft versus host disease.

Graft versus host disease (GVHD) remains the major complication of allogeneic bone marrow transplantation. T cells in the donor bone marrow recognize and react against host alloantigens and thereby initiate GVHD, but the precise mechanisms by which host tissues are damaged remain unclear. Recently, several convergent lines of evidence have suggested that inflammatory cytokines act as mediators of acute GVHD. Most of the clinical manifestations of GVHD may in fact be due to the dysregulated production of cytokines by T cells and other inflammatory cells. The complex interactions among cytokines and their cellular targets suggest that individual cytokines may play an important and distinctive role in the pathophysiology of GVHD. Perturbation of the cytokine network may function as a final common pathway of target organ damage, and the rapid onset of severe, acute GVHD can be considered a 'cytokine storm.'