Establishment of harmonization in immunophenotyping: A comparative study of a standardized one-tube lymphocyte-screening panel.

BACKGROUND: Multiparameter flow cytometry has been increasingly used in the identification and characterization of leukemia and lymphoma. However, due to technical complexity, this method still presents some level of variation between laboratories. In an attempt to yield more reproducible results, restrictive, highly standardized procedures have been proposed. The objective of this work was to compare this standardized protocol to a more open and flexible procedure. METHODS: The levels of expression of markers from the Euroflow lymphoid screening tube (LST) panel were evaluated on a population of both healthy and diseased patients using the recommended monoclonal antibody (MoAb) combinations or an alternative combination of either different MoAb clones or different dyes. Results were expressed as the percentages of positive target cells for each marker. RESULTS: Our study shows excellent correlation between the two methods demonstrating that comparable results can be achieved through harmonization of the procedures rather than through the constraints of standardization. CONCLUSION: Our results demonstrate that the harmonization approach is feasible. This frees scientists from the restrictions imposed by a standardization approach.

Standardization of flow cytometry in myelodysplastic syndromes: a report from an international consortium and the European LeukemiaNet Working Group.

Flow cytometry (FC) is increasingly recognized as an important tool in the diagnosis and prognosis of myelodysplastic syndromes (MDS). However, validation of current assays and agreement upon the techniques are prerequisites for its widespread acceptance and application in clinical practice. Therefore, a working group was initiated (Amsterdam, 2008) to discuss and propose standards for FC in MDS. In 2009 and 2010, representatives from 23, mainly European, institutes participated in the second and third European LeukemiaNet (ELN) MDS workshops. In the present report, minimal requirements to analyze dysplasia are refined. The proposed core markers should enable a categorization of FC results in cytopenic patients as 'normal', 'suggestive of', or 'diagnostic of' MDS. An FC report should include a description of validated FC abnormalities such as aberrant marker expression on myeloid progenitors and, furthermore, dysgranulopoiesis and/or dysmonocytopoiesis, if at least two abnormalities are evidenced. The working group is dedicated to initiate further studies to establish robust diagnostic and prognostic FC panels in MDS. An ultimate goal is to refine and improve diagnosis and prognostic scoring systems. Finally, the working group stresses that FC should be part of an integrated diagnosis rather than a separate technique.

Aberrant marker expression patterns on the CD34+CD38- stem cell compartment in acute myeloid leukemia allows to distinguish the malignant from the normal stem cell compartment both at diagnosis and in remission.

Acute myeloid leukemia (AML) is generally regarded as a stem cell disease. In CD34-positive AML, the leukemic stem cell has been recognized as CD38 negative. This CD34+CD38- population survives chemotherapy and is most probable the cause of minimal residual disease (MRD). The outgrowth of MRD causes relapse and MRD can therefore serve as a prognostic marker. The key role of leukemogenic CD34+CD38- cells led us to investigate whether they can be detected under MRD conditions. Various markers were identified to be aberrantly expressed on the CD34+CD38- population in AML and high-risk MDS samples at diagnosis, including C-type lectin-like molecule-1 and several lineage markers/marker-combinations. Fluorescent in situ hybridization analysis revealed that marker-positive cells were indeed of malignant origin. The markers were neither expressed on normal CD34+CD38- cells in steady-state bone marrow (BM) nor in BM after chemotherapy. We found that these markers were indeed expressed in part of the patients on malignant CD34+CD38- cells in complete remission, indicating the presence of malignant CD34+CD38- cells. Thus, by identifying residual malignant CD34+CD38- cells after chemotherapy, MRD detection at the stem cell level turned out to be possible. This might facilitate characterization of these chemotherapy-resistant leukemogenic cells, thereby being of help to identify new targets for therapy.

Refractory coeliac disease: a window between coeliac disease and enteropathy associated T cell lymphoma.

The treatment of coeliac disease (CD) is straightforward and simple: life-long adherence to a gluten-free diet. However, in a small subgroup of patients, the clinical and histological abnormalities persist or recur. This non-responsiveness leaves a poorly understood syndrome known as refractory coeliac disease (RCD). A specific definition of RCD is lacking in the literature. We speculate that RCD may appear in a subgroup of coeliacs with persisting histologic abnormalities. In all patients screened for RCD we look for DQ2 and DQ8. In non-DQ2/DQ8 patients we reconsider the diagnosis of CD and of auto-immune enteropathy. Most of the patients referred to us because of suspicion of RCD are affected by other diseases. Probably the commonest cause of non-responsiveness is continued gluten intake. Exocrine pancreas insufficiency, hyperthyroid disease, collagenous colitis are other common explanations. RCD and enteropathy-associated T cell lymphomas (EATL) can be distinguished by intra-epithelial lymphocyte phenotyping and TCR-gamma gene rearrangements. In RCD, an unexplained sustained stimulation of T cell cytotoxic activity is present. Immunosuppressive treatment might moderate this. Cyclosporine has been reported as a resounding success in case reports; however, our results were disappointing. We suggest azathioprine and steroids in RCD without aberrant T-lymphocytes in their mucosa. However, in RCD with aberrant T-lymphocytes we suggest chemotherapy. As the prognosis of EATLs is extremely poor the early detection of RCD with aberrant T cells is crucial.