Friederike Kreisel

Cutting Edge: Murine Vascular Endothelium Activates and Induces the Generation of Allogeneic CD4+25+Foxp3+ Regulatory T Cells

Unlike graft-resident donor-derived hemopoietic APCs, which decrease in number over time after transplantation, vascular endothelial cells are lifelong residents of a vascularized allograft. Endothelial cells are potent APCs for allogeneic CD8+ T lymphocytes but are unable to induce proliferation of allogeneic CD4+ T lymphocytes. Although the reason for this differential response has been poorly understood, here we report that alloantigen presentation by vascular endothelium to CD4+ T lymphocytes activates and induces CD4+25+Foxp3+ regulatory T cells, which can inhibit proliferation of alloreactive T cells both in vitro and in vivo. This process occurs independently of B7.1 costimulation but is dependent on programmed death ligand 1 (B7-H1). This finding may have important implications for tolerance induction in transplantation.

Cutting edge: acute lung allograft rejection is independent of secondary lymphoid organs

It is the prevailing view that adaptive immune responses are initiated in secondary lymphoid organs. Studies using alymphoplastic mice have shown that secondary lymphoid organs are essential to initiate allograft rejection of skin, heart, and small bowel. The high immunogenicity of lungs is well recognized and allograft rejection remains a major contributing factor to poor outcomes after lung transplantation. We show in this study that alloreactive T cells are initially primed within lung allografts and not in secondary lymphoid organs following transplantation. In contrast to other organs, lungs are acutely rejected in the absence of secondary lymphoid organs. Two-photon microscopy revealed that recipient T cells cluster predominantly around lung-resident, donor-derived CD11c+ cells early after engraftment. These findings demonstrate for the first time that alloimmune responses following lung transplantation are initiated in the graft itself and therefore identify a novel, potentially clinically relevant mechanism of lung allograft rejection.

State of the art in myeloid sarcoma

Introduction:  Myeloid sarcomas are extramedullary lesions composed of myeloid lineage blasts that typically form tumorous masses and may precede, follow, or occur in the absence of systemic acute myeloid leukemia. They most commonly involve the skin and soft tissues, lymph nodes, and gastrointestinal tract and are particularly challenging to diagnose in patients without an antecedent history of acute myeloid leukemia.

Combined Core Needle Biopsy and Fine-Needle Aspiration With Ancillary Studies Correlate Highly With Traditional Techniques in the Diagnosis of Nodal-Based Lymphoma

Core needle biopsy (CNB) and fine-needle aspiration (FNA) are increasingly replacing excisional lymph node biopsy in the diagnosis of lymphomas. However, evaluation of CNB and FNA remains challenging owing to limited architectural information and the more detailed subclassification of lymphomas required by the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. Our study is the largest study to assess diagnostic accuracy of CNB and FNA in conjunction with ancillary studies. We analyzed 263 cases and a diagnosis was established in 237, of which 193 were completely subclassified. In cases in which excisional biopsy was available as a reference for comparison, CNB and FNA had a sensitivity of 96.5%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 90%. CNB and FNA with ancillary studies represent a viable alternative in the diagnosis of lymphoma, as long as the number and size of cores for morphologic studies are not compromised.

Assessment of Cellular Proliferation in Tumors by PET Using 18F-ISO-1

This first study in humans was designed to evaluate the safety and dosimetry of a cellular proliferative marker, N-(4-(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)butyl)-2-(2-18F-fluoroethoxy)-5-methylbenzamide (18F-ISO-1), and evaluate the feasibility of imaging tumor proliferation by PET in patients with newly diagnosed malignant neoplasms. Methods: Patients with biopsy-proven lymphoma, breast cancer, or head and neck cancer underwent 18F-ISO-1 PET. Tumor 18F-ISO-1 uptake was assessed semiquantitatively by maximum standardized uptake value, ratios of tumor to normal tissue and tumor to muscle, and relative distribution volume ratio. The PET results were correlated with tumor Ki-67 and mitotic index, from in vitro assays of the tumor tissue. The biodistribution of 18F-ISO-1 and human dosimetry were evaluated. Results: Thirty patients with primary breast cancer (n = 13), head and neck cancer (n = 10), and lymphoma (n = 7) were evaluated. In the entire group, tumor maximum standardized uptake value and tumor-to-muscle ratio correlated significantly with Ki-67 (τ = 0.27, P = 0.04, and τ = 0.38, P = 0.003, respectively), but no significant correlation was observed between Ki-67 and tumor–to–normal-tissue ratio (τ = 0.07, P = 0.56) or distribution volume ratio (τ = 0.26, P = 0.14). On the basis of whole-body PET data, the gallbladder is the dose-limiting organ, with an average radiation dose of 0.091 mGy/MBq. The whole-body and effective doses were 0.012 mGy/MBq and 0.016 mSv/MBq, respectively. No adverse effects of 18F-ISO-1 were encountered. Conclusion: The presence of a significant correlation between 18F-ISO-1 and Ki-67 makes this agent promising for evaluation of the proliferative status of solid tumors. The relatively small absorbed doses to normal organs allow for the safe administration of up to 550 MBq, which is sufficient for PET imaging in clinical trials.

CCR2 Regulates Monocyte Recruitment As Well As CD4+ Th1 Allorecognition After Lung Transplantation

Graft rejection remains a formidable problem contributing to poor outcomes after lung transplantation. Blocking chemokine pathways have yielded promising results in some organ transplant systems. Previous clinical studies have demonstrated upregulation of CCR2 ligands following lung transplantation. Moreover, lung injury is attenuated in CCR2‐deficient mice in several inflammatory models. In this study, we examined the role of CCR2 in monocyte recruitment and alloimmune responses in a mouse model of vascularized orthotopic lung transplantation. The CCR2 ligand MCP‐1 is upregulated in serum and allografts following lung transplantation. CCR2 is critical for the mobilization of monocytes from the bone marrow into the bloodstream and for the accumulation of CD11c+ cells within lung allografts. A portion of graft‐infiltrating recipient CD11c+ cells expresses both recipient and donor MHC molecules. Two‐photon imaging demonstrates that recipient CD11c+ cells are associated with recipient T cells within the graft. While recipient CCR2 deficiency does not prevent acute lung rejection and is associated with increased graft infiltration by T cells, it significantly reduces CD4+ Th1 indirect and direct allorecognition. Thus, CCR2 may be a potential target to attenuate alloimmune responses after lung transplantation.

Sphingosine 1-phosphate inhibits ischemia reperfusion injury following experimental lung transplantation

Ischemia reperfusion (I/R) injury following lung transplantation is exacerbated by the destruction of the endothelial cell barrier leading to pulmonary edema and dysregulated activated lymphocyte migration. Sphingosine 1‐phosphate (S1P), a G‐coupled protein receptor (GPCR) agonist, has been previously shown to promote endothelial cell tight junction formation and prevent monocyte chemotaxis. We asked if S1P treatment could improve pulmonary function and attenuate I/R injury following syngeneic rat lung transplantation. In comparison to vehicle‐treated recipients, S1P administered before reperfusion significantly improved recipient oxygenation following transplantation. Improved graft function was associated with reduced inflammatory signaling pathway activation along with attenuated intragraft levels of MIP‐2, TNF‐α and IL‐1β. Moreover, S1P‐treated recipients had significantly less apoptotic endothelial cells, pulmonary edema and graft accumulation of neutrophils than did vehicle‐treated recipients. Thus our data show that S1P improves lung tissue homeostasis following reperfusion by enhancing endothelial barrier function and blunting monocytic graft infiltration and inflammation.

CD4+ T Lymphocytes Are Not Necessary for the Acute Rejection of Vascularized Mouse Lung Transplants

Acute rejection continues to present a major obstacle to successful lung transplantation. Although CD4+ T lymphocytes are critical for the rejection of some solid organ grafts, the role of CD4+ T cells in the rejection of lung allografts is largely unknown. In this study, we demonstrate in a novel model of orthotopic vascularized mouse lung transplantation that acute rejection of lung allografts is independent of CD4+ T cell-mediated allorecognition pathways. CD4+ T cell-independent rejection occurs in the absence of donor-derived graft-resident hematopoietic APCs. Furthermore, blockade of the CD28/B7 costimulatory pathways attenuates acute lung allograft rejection in the absence of CD4+ T cells, but does not delay acute rejection when CD4+ T cells are present. Our results provide new mechanistic insight into the acute rejection of lung allografts and highlight the importance of identifying differences in pathways that regulate the rejection of various organs.

CD163 Immunohistochemistry Is Superior to CD68 in Predicting Outcome in Classical Hodgkin Lymphoma

OBJECTIVES In recent years, research has increasingly focused on the microenvironment of classical Hodgkin lymphoma (CHL) as a predictor of treatment outcome. The focus of this study was to assess the interobserver reproducibility in interpreting macrophage-associated immunohistochemistry (IHC) for CD68 and CD163 in a retrospective cohort of 88 patients with CHL. METHODS Staining results were correlated with clinical outcome in all patients and those with a high international prognostic score (IPS). RESULTS The intraclass correlation (ICC) for the five hematopathologists interpreting the IHC was stronger for CD163 (0.70) than for CD68 (0.50). Using a cutoff of 25% mean macrophage reactivity and including all patients, a statistically significant difference in overall survival (OS) was seen only for CD163 (P = .0006) and not for CD68 (P = .414). Patients with a mean CD163 reactivity of 25% or more had a median OS of 71 months vs 101 months for patients with less than 25% reactivity. CD163 retained statistical significance in multivariate analysis. In patients with advanced-stage CHL with high IPS, OS was also significantly worse for those with a mean CD163 reactivity of 25% or higher. CONCLUSIONS Our study confirms previous reports of a prognostic role of tumor-infiltrating macrophages in CHL, but only for CD163. Although most of the literature supports an increasing role of macrophage IHC as a predictor of clinical outcome, successful clinical translation will require a standardized method and reporting system.

Murine Gammaherpesvirus 68 Genes both Induce and Suppress Lymphoproliferative Disease

ABSTRACT Gammaherpesvirus infection is associated with an increased incidence of lymphoproliferative disease in immunocompromised hosts. Murine gammaherpesvirus 68 (γHV68) infection of BALB β2-microglobulin-deficient (BALB β2m−/−) mice provides an animal model for analysis of the mechanisms responsible for the induction of a lymphoproliferative disease, atypical lymphoid hyperplasia (ALH), that is pathologically similar to posttransplant lymphoproliferative disease associated with Epstein-Barr virus infection. Here we report that the γHV68 v-cyclin and v-bcl-2 genes are required for the efficient induction of γHV68-associated ALH in BALB β2m−/− mice, while the v-GPCR gene is dispensable for ALH induction. In contrast to these findings, deletion of the viral M1 gene enhanced ALH. Thus, γHV68 genes can either inhibit or enhance the induction of lymphoproliferative disease in immunocompromised mice.