Doctor of Medicine, Universitat Ulm (2010)
Lag-3 has emerged as an important molecule in T cell biology. We investigated the role of Lag-3 in conventional T cell (Tcon) and regulatory T cell (Treg) function in murine GVHD with the hypothesis that Lag-3 engagement diminishes alloreactive T cell responses after bone marrow transplantation. We demonstrate that Lag-3 deficient Tcon (Lag-3(-/-) Tcon) induce significantly more severe GVHD than wild type (WT) Tcon and that the absence of Lag-3 on CD4 but not CD8 T cells is responsible for exacerbating GVHD. Lag-3(-/-) Tcon exhibited increased activation and proliferation as indicated by CFSE and bioluminescence imaging analyses and higher levels of activation markers such as CD69, CD107a, granzyme B, and Ki-67 as well as production of IL-10 and IFN-g early after transplantation. Lag-3(-/-) Tcon were less responsive to suppression by WT Treg as compared to WT Tcon. The absence of Lag-3, however, did not impair Treg function as both Lag-3(-/-) and WT Treg equally suppress the proliferation of Tcon in vitro and in vivo and protect against GVHD. Further, we demonstrate that allogeneic Treg acquire recipient MHC class II molecules through a process termed trogocytosis. As MHC class II is a ligand for Lag-3, we propose a novel suppression mechanism employed by Treg involving the acquisition of host MHC-II followed by the engagement of Lag-3 on T cells. These studies demonstrate for the first time the biologic function of Lag-3 expression on conventional and regulatory T cells in GVHD and identify Lag-3 as an important regulatory molecule involved in alloreactive T cell proliferation and activation after bone marrow transplantation.
View details for DOI 10.1371/journal.pone.0086551
View details for PubMedID 24475140
Alloreactivity of donor lymphocytes leads to graft-versus-host disease (GVHD) contributing to significant morbidity and mortality following allogeneic hematopoietic cell transplantation (HCT). Within the past decade, significant progress has been made in elucidating the mechanisms underlying the immunologic dysregulation characteristic of GVHD. The recent discoveries of different cell subpopulations with immune regulatory function has led to a number of studies aimed at understanding their role in allogeneic HCT and possible application for the prevention and treatment of GVHD and a host of other immune-mediated diseases. Preclinical animal modeling has helped define the potential roles of distinct populations of regulatory cells that have progressed to clinical translation with promising early results.
View details for DOI 10.1182/blood-2013-08-453126
View details for PubMedID 24068494
Patients with primary refractory or relapsed acute myeloid leukemia (AML) have a dismal prognosis. We report a retrospective single center analysis of aplasia-inducing chemotherapy using fludarabine, cytarabine, and amsacrine (FLAMSA) followed by reduced-intensity conditioning (RIC) for allogeneic hematopoietic cell transplantation (HCT) in 62 consecutive primary refractory or relapsed AML patients. Two-year event-free survival and overall survival (OS) were 26 and 39 %, respectively. Risk stratification according to cytogenetic and molecular genetic markers showed superior survival in patients in the intermediate-1 risk group (2-year OS 70 %) compared to the intermediate-2 risk (2-year OS 34 %, p?=?0.03) and adverse risk (2-year OS 38 %, p?=?0.06) group. The use of HLA-matched versus HLA-mismatched donors had no significant influence on survival (p?=?0.98). Two-year OS in the elderly subgroup defined by age ?60 years was 31 % compared to 46 % in the group of younger patients <60 years (p?=?0.19). Cumulative incidence of non-relapse mortality at 2 years adjusted for relapse as competing risk was 20 % for patients <60 years and 26 % for older patients (p?=?0.55). Chronic graft-versus-host disease was associated with a statistically significant superior survival (p?0.01). FLAMSA-RIC followed by allogeneic HCT enables long-term disease-free survival in primary refractory or relapsed AML even in the elderly patient population.
View details for PubMedID 23652585
Mucormycosis is a serious invasive fungal infection in immunocompromised patients. Patients undergoing treatment for hematologic malignancies are predominantly prone to the pulmonary manifestation of mucormycosis. Historically, allogeneic hematopoietic cell transplantation (HCT) in patients suffering from pulmonary mucormycosis (PM) was considered contraindicated owing to mortality rates up to 90%. We present 3 patients with acute myeloid leukemia and PM who were treated with radical surgical debridement combined with high-dose liposomal amphotericin B (LAB), and subsequently underwent successful allogeneic HCT. To date, all 3 patients are in complete remission and show no signs of mucormycosis. Allogeneic HCT in patients with PM seems feasible provided that the infectious focus is completely removed surgically and adequate antifungal pharmacotherapy, such as high-dose LAB or posaconazole, is established.
View details for DOI 10.1111/tid.12019
View details for Web of Science ID 000312149100009
View details for PubMedID 23075207
HISTORY AND ADMISSION FINDINGS: A 27-year-old male patient with a past medical history of HIV presented with acute myeloid leukemia for allogeneic hematopoietic stem cell transplantation (HSCT). Highly active anti-retroviral therapy suppressed the viral load below detection threshold. INVESTIGATIONS: There were no contraindications for allogeneic HSCT. TREATMENT AND COURSE: Myeloablative conditioning consisted of total body irradiation and cyclophosphamide. Anti-thymocyte globulin, tacrolimus and mycophenolate mofetil were used for immunosuppression. Combined anti-retroviral therapy (nucleoside and nucleotide analog reverse-transcriptase inhibitor, boostered protease inhibitor, maraviroc and raltegravir) was maintained for allogeneic HSCT and viral load remained below detection threshold. No graft-versus-host disease or serious infectious complications occurred. The patient showed good graft function with stable hematopoiesis. Localized Kaposi's sarcoma was diagnosed six months after allogeneic HSCT and treated successfully with surgical excision and reduction of immunosuppression. Almost one year after allogeneic HSCT, the CD4+ cell count is rising and viral load remains below detection threshold with combined anti-retroviral therapy. Conclusion: Allogeneic HSCT can be safely performed in HIV positive patients. Kaposi's sarcoma is a rare event after allogeneic HSCT and linked to strong immunosuppression.
View details for DOI 10.1055/s-0031-1299022
View details for PubMedID 22374660
Polyomavirus BK (BKV) is known as an important etiologic agent in the development of hemorrhagic cystitis (HC) after allogeneic stem cell transplant (SCT). To define T cell epitopes of the BKV proteins VP1 and sT, eight potential HLA-A2-binding peptides were synthesized based on computer algorithms. These peptides were co-incubated with CD8 + T cells from the peripheral blood (PB) of 25 healthy volunteers and seven patients suffering from HC after allogeneic SCT in a mixed-lymphocyte peptide culture (MLPC), which were subsequently screened by enzyme-linked immunospot (ELISPOT) assays and fluorescence-activated cell sorting (FACS) analysis. We found that CD8 + T cells from five of seven (71%) patients with HC presensitized with the BKV peptide VP1 p108 (LLMWEAVTV) specifically recognized T2 cells pulsed with VP1 p108. In contrast, only seven of 25 (28%) healthy volunteers had CD8 + T cells reactive with VP1 p108-pulsed T2 cells. The presence of VP1 p108-specific T cells could be confirmed by FACS analysis. The BKV peptide VP1 p108 seems to play an important role as an immunodominant peptide in the pathogenesis of HC in patients after allogeneic SCT, and might be a promising target for immunotherapies or even strategies to prevent the development of BKV-associated HC.
View details for DOI 10.3109/10428191003746323
View details for Web of Science ID 000279485300016
View details for PubMedID 20370539