The ICCS-recommended high-sensitivity flow cytometry protocol was effective for detecting major and minor PNH clones in Russian PNH patients, and showed high reproducibility between laboratories.

It has been proposed that circulating HSCs play a role in graft survival after liver transplantation. The aim was to analyze the relationship between the number of HSCs before and after LDLT and liver function, immune biomarkers, and clinical outcomes in pediatric patients. We studied 15 pairs of adult healthy liver donors and pediatric recipients with ESLD. The CD34/CD45+ cell number was measured in the blood via flow cytometry, and plasma levels of immune biomarkers - via ELISA. CD34/CD45+ cell number in the recipients decreased within the first week after LDLT. The cell number before LDLT was negatively correlated with the plasma levels of CRP and the development of graft dysfunction in the early post-transplant period. After LDLT, the CD34/CD45+ cell number was positively correlated with the pretransplant plasma level of sCD40L, a T-cell activation marker. In adult liver donors, the cell number did not change within the first week after liver resection and was lower than in pediatric recipients. The results suggest that in pediatric recipients, the HSC number may be associated with graft function and could be regarded as a potential predictor of the clinical outcome after LDLT.

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Introduction. Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematopoietic stem cell disorder resulting from the somatic mutation of the X-linked phosphatidylinositolglycan complementation Class A (PIG-A) gene. PIGA mutations in PNH patients lead to a glycosylphosphatidylinositol (GPI)-linked membrane proteins expression deficiency.In PNH, there is a partial or absolute inability to make GPI-anchored proteins including complement-defense structures such as CD55 and CD59 on RBCs and WBCs. Clinical features of PNH include intravascular hemolysis, bone marrow failure, and thrombosis, all major causes of morbidity and mortality. Flow cytometry (FCM) plays a key role in the laboratory investigation of PNH, and rapid diagnosis of this condition is highly desirable. A definitive diagnosis of PNH can be established by demonstrating the absence of cell membraneGPI-anchored proteins from granulocytes or red blood cells (RBC) according to ICCS Guidelines for the diagnosis and monitoring of PNH by flow cytometry. It has been also described that the expression of CD16 can be decreased on PNH-affected granulocytes. Recently new method for extended flow WBC differential was introduced by Beckman Coulter. This method uses flow cytometric analysis with CytoDiff™** reagents which is a 5-color/6-marker reagent that provides a 10-part cytometric differential from whole blood specimens and comprises CD36-FITC, (CD2+CD294)-PE, CD19-ECD, CD16-PC5, and CD45-PC7 (Beckman Coulter). The protocol allows detection of mature neutrophils, total lymphocytes, total monocytes, eosinophils, basophils, immature granulocytes, B lymphocytes, CD16-negative T/NK lymphocytes, CD16-positive T/NK lymphocytes, CD16 positive and CD16 negative monocytes, and blasts cells with lineage orientation. This method also allows the detection of the abnormal antigen expression on WBC, for example low CD16 expression on neutrophils. In case of abnormal low CD16 expression on segmented neutrophils they will be classified as Immature Granulocytes (Imm Gran). The aim of the study was to evaluate the efficacy of CytoDiff** analysis of peripheral blood for PNH screening detecting low CD16 expression on neutrophils. Methods: EDTA-anticoagulated blood samples from 53 patients with PHN suspicion were prospectively included in the study. Analysis of the PNH clones was conducted in according with international protocol, using CD235a for RBC gating, CD15-PE/CD45-PC7 for granulocyte gating, CD64-PC5/CD45-PC7 for monocyte gating and GPI-anchored proteins CD59-PE, FLAER-FITC/CD24-PC5 and FLAER-FITC/CD14-PE for RBCs, granulocytes and monocytes accordingly. For extended flow WBC differential analysis the blood samples were stained with the CytoDiff** panel, lyzed with Versalyse (Beckman Coulter) and 20 000 leucocytes were analyzed on a FC500 Flow Cytometer (Beckman Coulter) using CytoDiff** CXP software. Results:Totally 53 patients with PHN suspicion were prospectively included in the study. All these patients were characterized by anemia, thrombocytopenia and/or leucopenia. PNH diagnosis was confirmed in 6 patients and in other 7 patients the final diagnosis was aplastic anemia with PNH clone. For all 13 patients (4 males, 9 females, with median age of 41.5 years) with confirmed presence of PNH clone CytoDiff** reported increased number of Imm Gran (range 3-45%). Microscopy analysis did not detect the presence of Imm Grans in the slide, so we concluded that falsely reported increased Imm Gran count was due to the decreased expression of CD16 on Neutrophils. Good correlation (r=0.9257) was observed between Imm Gran count and the size of granulocytic PNH clone. Conclusion: Our data demonstrate that CytoDiff** analysis, which is able to detect a wide spectrum of normal and pathological cells in peripheral blood allows determination of CD16-low expression on neutrophils and thus provide efficient screening for suspicious of PNH in patients with anemic syndrome. ** Not available in the United States and other geographies. Disclosures Lugovskaya: Beckman Coulter: Research Funding.

Profound immunological dysfunction is the key factor determining the development of infectious complications in chronic lymphocytic leukemia (CLL). The aim of this work is to assess the features of the subpopulation composition of T-lymphocytes (T-helpers (Th), cytotoxic T-lymphocytes (Tcyt), T regulatory cells (Treg), T-NK cells, naive Th, Th-memory, activated T-lymphocytes, TCRγδ cells) and NK cells in peripheral blood of patients with newly diagnosed chronic lymphocytic leukemia (CLL) and receiving ibrutinib therapy. Hematological and immunophenotypic studies have been performed in 30 patients with previously untreated CLL, 122 patients on ibrutinib therapy and 20 healthy donors. The subpopulation composition of T-lymphocytes (Th, Tcyt, Treg, T-NK, naive T-helpers, memory T-helpers, TCRγδ cells, activated T-lymphocytes) and NK cells has been assessed on flow cytometer (FACSCanto II (BD)) using the following panel of monoclonal antibodies: CD45, CD19, CD3, CD4, CD5, CD8, TCRγδ, CD127, CD16, CD56, CD57 CD45RA, CD45R0, HLA-DR, CD25. Compared to controls all CLL samples were found to have higher the absolute number of T-lymphocytes, NK cells and their subpopulations, T-helpers (especially of memory T-cells), cytotoxic T-cells, regulatory T-cells, TCRγδ T-cells, activated T-lymphocytes, increased cytotoxic potential of NK cells in previously untreated CLL patients. Patients who received ibrutinib therapy have registered a positive trend towards recovery of the subpopulation composition of T-lymphocytes and NK-cells. CLL patients have been found to have quantitative and functional changes in the subpopulations of T-lymphocytes and NK cells, indicating dysregulation of the immune response, and a high risk of developing infections. Monitoring of immunological parameters for ibrutinib therapy make possible to estimate impact of ibrutinib on the adaptive anti-CLL immune response.