Immune responses against monocytotropic ehrlichiosis during infection with a strain of Ehrlichia fromIxodes ovatus (IOE) were evaluated using a model that closely reproduces the pathology and immunity associated with tick-transmitted human monocytotropic ehrlichiosis. C57BL/6 mice were inoculated intradermally or intraperitoneally with high-dose highly virulent IOE or intraperitoneally with mildly virulent Ehrlichia muris. Intradermal (i.d.) infection with IOE established mild, self-limited disease associated with minimal hepatic apoptosis, and all mice survived past 30 days. Intraperitoneal (i.p.) infection with IOE resulted in acute, severe toxic shock-like syndrome and severe multifocal hepatic apoptosis and necrosis, and all mice succumbed to disease. Compared to i.p. infection with IOE, intradermally infected mice had a 100-to 1,000-fold lower bacterial load in the spleen with limited dissemination. Compared to mice infected intraperitoneally with IOE, i.d. infection stimulated a stronger protective type-1 cell-mediated response on day 7 of infection, characterized by increased percentages of both CD4؉ and CD8 ؉ splenic T cells, generation of a greater number of IOE-specific, gamma interferon-producing CD4 ؉ Th1 cells, and higher levels of tumor necrosis factor (TNF-␣) in the spleen but lower concentrations of serum TNF-␣ and interleukin-10. These data suggest that under the conditions of natural route of challenge (i.e., i.d. inoculation), the immune response has the capacity to confer complete protection against monocytotropic ehrlichiosis, which is associated with a strong cellmediated type-1 response and decreased systemic production of pro-and anti-inflammatory cytokines.Human monocytotropic ehrlichiosis (HME) is an emerging infection in humans, and is the most prevalent life-threatening tick-borne disease in North America (20). Ehrlichia chaffeensis, the etiologic agent of HME, is an obligately intracellular bacterium (30) which causes a range of manifestations, from mild to severe, in immunocompetent patients. HME can be fatal, particularly in immunocompromised (22, 31) or elderly individuals (19).Several animal models have been developed to examine the factors that determine host resistance or susceptibility to ehrlichiosis. E. chaffeensis does not cause disease in immunocompetent mice. Although E. chaffeensis infection in SCID mice provided some clues to the immune response to Ehrlichia (i.e., the importance of T cells, gamma interferon [IFN-␥], and antibodies in clearing infection) (4, 9, 35), the pathology does not mimic HME. Two different strains of Ehrlichia, Ehrlichia muris (21) and the unnamed strain isolated from Ixodes ovatus ticks (IOE) (27), have provided better models that mimic the pathology and clinical manifestations of HME. However, the antigenic and genetic differences between E. muris and IOE could be confounding factors in the interpretation of the results when comparing these models (26,32). Models using the same organism provide a more advantageous situation to study differences...

Assessment of ERBB2 (HER2) status in breast carcinomas has become critical in determining response to the humanised monoclonal antibody trastuzumab. The current joint College of American Pathologists and the American Society of Clinical Oncology guidelines for the evaluation of HER2 status in breast carcinoma involve testing by immunohistochemistry and fluorescence in situ hybridisation (FISH). However, neither of these modalities is without limitations. Novel bright field in situ hybridisation techniques continue to provide viable alternatives to FISH testing. While these techniques are not limited to evaluation of the HER2 gene, the extensive number of studies comparing bright field in situ techniques with other methods of assessing HER2 status allow a robust evaluation of this approach. Analysis of the literature demonstrates that, when used to assess HER2 gene status, bright field in situ hybridisation demonstrates excellent concordance with FISH results. The average percentage agreement in an informal analysis of studies comparing HER2 amplification by chromogenic in situ hybridisation with FISH was 96% (SD 4%); κ coefficients ranged from 0.76 to 1.0. Although a much smaller number of studies are available for review, similar levels of concordance have been reported in studies comparing HER2 amplification by methods employing metallography (silver in situ hybridisation) with FISH. A summary of the advancements in bright field in situ hybridisation, with focus on those techniques with clinical applications of interest to the practicing pathologist, is presented.

Background. Multisystem inflammatory disorder in children and adolescents is a relatively new and rare complication of COVID-19. This complication seems to develop after the infection rather than during the acute phase of COVID-19. The clinical features are similar to a well-known inflammatory syndrome in children, Kawasaki disease, and it can lead to collapse and multiple organ failure requiring intensive care. The COVID-19-associated multisystem inflammatory syndrome in children and adolescents is referred to mutually as pediatric inflammatory multisystem syndrome temporally linked with SARS-CoV-2 (PIMS-TS) or multisystem inflammatory syndrome in children (MIS-C) correlated with COVID-19, and here, it is referred to as MIS-C. Case Presentation. This report describes a nine-month-old Asian infant presented with a two-week history of fever with nonspecific signs of viral illness and erythematous rash. The clinical and biochemical findings were compatible with complicated typical Kawasaki disease (KD). The infant fulfilled the World Health Organization criteria for MIS-C and was treated with intravenous immunoglobulin and anticoagulation, which he responded well to. He was discharged home in good condition after almost 3 weeks of treatment. Conclusion. This case highlights a rare but new phenomenon attributed to severe acute respiratory syndrome coronavirus 2 infection. We report the first case report of MIS-C in the United Arab Emirates and Arab region. Among KD’s complications, massive aneurysm with thrombosis is rare and usually will have deleterious results if not diagnosed and managed promptly.

Introduction: Chronic myelomonocytic leukemia (CMML) is a heterogeneous group of bone marrow disorders currently grouped into the MDS/MPD overlap by WHO classification. Its clinical and laboratory features includes the presence of up to 20% blast in the bone marrow and the peripheral blood, a PB monocyte count >1000/mL, splenomegaly, variable reticulin fibrosis in the bone marrow and cytopenias. The exact pathogenesis remains in question and there are no effective therapies. Recent studies in certain myeloid disorders suggest that the nuclear transcription factor NFkB regulates cell survival, proliferation, and differentiation. It has been found to be highly expressed in AML and may serve as an important therapeutic target. Little is known about NFkB in other hematologic disorders, including CMML. Examination of NFkB activation in situ has been technically difficult due to lack of quality antibody reagents suitable for fixed tissues. Recently, phosphospecific antibodies have become available, which reflect the functional status of proteins. IkB regulates NFkB subunits by sequestering them in the cytoplasm. Phosphorylation of IkB by IKK results in release of NFkB and translocation to the nucleus. Thus, phospho-IkB (pIkB) is an indicator of NFkB activation. We studied the pattern of pIkB expression in CMML as a surrogate of NFkB activation. Methods: We identified a cohort of 24 CMML (CMML1=17; CMML2=7) patients and 9 healthy controls. Cases were characterized clinically and pathologically. Immunohistochemistry (IHC) for pIkB was performed in trephine biopsies using a phosphor-specific antibody (Cell Signaling). The staining pattern was compared to normal bone marrow. We utilized JMP 5.1.2 statistical software to compare a variety of clinical and laboratory parameters. Results: The mean age of patients at diagnosis was 61 (range:38–72). Median WBC, Hgb, PLT, absolute monocytes were 18.6K/ul, 10.2g/dL, 93K/ul, 4K/ul respectively. As expected, the overall survival (OS) was short (mean OS = 11.1 months). Compared to normal bone marrow, pIkB was found to be abnormally activated in maturing granulocytic cells and was found to be present in cytoplasmic as well as nuclear locations. The mean % neutrophils that expressed pIkB was 36.6 compared to 14.9 for normal bone marrow (P<0.00001). No clear association between OS or PFS was detected in this relatively small series based on neutrophil pIkB expression. However, neutrophil pIkB expression was correlated with higher WBC (R = 0.9, P=0.03) and absolute monocyte count (R =0.19, P=.04). Conclusions: An abnormal in situ pIkB expression pattern is present in CMML compared to normal bone marrow, suggesting abnormal activation of NFkB. Interestingly, maturing myeloid cell expression of pIKB was associated with higher WBC and absolute monocyte count. Further studies are warranted in examining the role of NFkB activation in CMML and potential therapeutic intervention in this pathway, such as with proteasome inhibitors.

Introduction: Diffuse Large B Cell Lymphoma (DLBL) is the most common type of Non-Hodgkin's Lymphoma (NHL) seen in Tawam hospital UAE. DLBL is a heterogenous disease arising either from a Germinal center (GC) or non- GCB cells. Molecular signature has identified 3 different groups of DLBL with significantly different prognosis (Primary mediastinal, Germinal center and Activated B Cell type). The therapy for DLBL has been without innovation since introduction of Rituximab more than 20 years ago and using R-CHOP. Attempts at improving the outcome has been uniformly unsatisfactory either by adding additional drugs, increasing the dose of drugs or deceasing the frequency of each cycle. New biomarkers and or targets are needed to improve the prognosis of patients with DLBL. Programmed Death-Ligand 1 (PDL1) has been shown to protect tumor cells by inducing T cell apoptosis (Dong et al., 2002). PDL1 targeting agents have been approved for many different types of malignancies including Hodgkin's Lymphoma. The role of PDL1 in DLBL is still under intense study. We report our findings of PDL1 expression in DLBL patients in UAE. Methods: Patients diagnosed with DLBL between December 1, 2019 till July 15th 2020. Patient records were reviewed in this study. Data was collected regarding patient demographics, clinical stage, International prognostic index (IPI), pathology and cell of origin {using immunohistochemistry (IHC) and Han's criteria}. PDL1 testing was performed by using FDA approved PharmaDx Dako Ab 22C3 kit for IHC on the gold standard Link 48 Dako platform. PDL1 expression was reported as Tumor proportion score (TPS). TPS in this assay was the percentage of viable tumor cells showing any perceptible partial or complete linear membranous (or membranous & cytoplasmic) staining, in the large lymphoma cells. The specimen was considered PDL1 positive if the TPS was greater than or equal to 30%(Xu-Monette et al Blood 2018). All scores were reported by single pathologist Results Twenty-six patients were diagnosed with DLBL in the study period. The median age was 44 years (range 18-90 years). Majority of patients (75%) were less than sixty years of age. Advanced stage disease was seen in preponderance (66%) as compared to early stage (34%) while the LDH was elevated in 65 % patients (institutional normal < 225 IU per liter). Majority of patients (60%) were poor risk with IPI 3 or higher. Pathology review showed a uniformly elevated Ki 67 with the majority of specimens showing greater than 80 %. Molecular classification showed GCB type 50 % (n=13) as compared to non-GCB 42 % (n=11), data was not available for 2 patients. Epstein-Barr virus encoded small RNA (EBER) CISH was positive in only 3 patients (data was not available for 8 patients). PDL1 expression was tested in eighteen (GCB n=8, ABC n=10) patients. PDL1 expression was elevated in ABC type (90%) as compared GCB type (50 %) Fig 1. Conclusion The median age (44 years) is at least 2 decades less than the reported western cohort. Majority of the patients had high risk disease with advanced stage and IPI. Ki 67 was uniformly elevated (>80 % in 90 % of patients). There was a slight preponderance of GCB type (50 % vs 42%). PDL1 expression in ABC type DLBL was higher as compared to GCB. This observation needs to be validated in a larger cohort. Recent literature makes it very clear that ABC type DLBL has a poor outcome as compared to GCB type. PDL1 may offer an attractive target for treatment evaluation in ABC type DLBL. Figure Disclosures Alam: Pfizer:Honoraria;Roche:Honoraria.McCarthy:Karyopharm:Consultancy, Honoraria;Magenta:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Janssen:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Takeda:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Juno Therapeutics, a Bristol-Myers Squibb Company:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board , Research Funding is to Roswell Park, Research Funding;AbbVie:Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board;Genentech:Consultancy, Honoraria;Starton:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board.

2016-12-24T18:10:15

No abstract

Idiopathic aplastic anemia (AA) is characterized by immune-mediated destruction of hematopoietic stem cells, leading to peripheral pancytopenia. Immune pathogenesis in AA is supported by experimental data, as well as clinical observations and may be related to the breach of peripheral or central tolerance. Regulatory T cells (Treg) constitute one of the most important mechanisms of central tolerance engaged in the down-modulation of autoreactive T cells. Tregs have been found to be reduced in several autoimmune diseases and decreased frequencies of Tregs were also reported in AA and MDS. Overexpression of the high affinity IL-2 receptor alpha chain (CD25) and the forkhead family transcription factor P3 (FoxP3), required for the development and function of Tregs, serve as phenotypic markers for Tregs. We investigated Treg levels in a cohort of AA patients (N=21) and healthy individuals (N=15); flow cytometric quantification of Treg was carried out after surface/intracellular staining of whole blood for Treg markers (CD3, CD4, CD25, FoxP3). After proper gating (light scatter properties, CD3, CD4, CD25), CD4+ T cells were subdivided into CD25−, CD25int and CD25hi populations, and the co-expression of CD25hi and Foxp3 was analyzed. In comparison to controls, AA patients (N=12) show not only lower frequencies of CD4+CD25hi+ T cells within the total lymphocyte population (median 0.07% vs. 0.21%; p=.03), but also absolute lower absolute numbers (1.31/uL vs. 5.78/uL, p=.0002). Similarly, CD4+CD25hi+FoxP3+ T cells were found to be depressed in untreated AA patients in comparison to controls (median 0.07% vs. 0.21% and 1.06/uL vs. 4.76/uL; p=.03 and p=.003). While Tregs were lower in patients with active disease unresponsive to immunosuppressive treatment (responder 0.1% vs non responder 0.07%, CD4+CD25hi Tcells, p=.02), serial testing performed in 6 patients treated with ATG/CsA did not reveal correlation between hematologic improvement and recovery of Treg numbers. When double immunohistochemical staining for CD3 and Foxp3 was performed in pre-treatment bone marrow core biopsies of AA patients (N=3) and controls (N=2) a mean of 3 CD3+Foxp3+ cells/10 high power fields (hpf) were counted (vs. mean 28/10 hpf, p<.05 in controls), suggesting that lower numbers of Tregs were also present in the bone marrow of AA patients. In conclusion, our results suggest that Tregs are decreased in blood and marrow of patients with idiopathic AA, consistent with the breach of peripheral tolerance in AA. In addition to flow cytometry, immunohistochemical staining of histologic specimens can be used for the quantitative analysis of Tregs in bone marrow failure syndromes and other immune-mediated conditions such as GvHD.