Franck Trimoreau

Extended diagnostic criteria for plasmacytoid dendritic cell leukaemia.

The diagnosis of plasmacytoid dendritic cell leukaemia (pDCL) is based on the immunophenotypic profile: CD4+ CD56+ lineageneg CD45RA+/ROneg CD11cneg CD116low CD123+ CD34neg CD36+ HLA‐DR+. Several studies have reported pDCL cases that do not express this exact profile or expressing some lineage antigens that could thus be misdiagnosed. This study aimed to validate pDCL‐specific markers for diagnosis by flow‐cytometry or quantitative reverse transcription polymerase chain reaction on bone marrow samples. Expression of markers previously found in normal pDC was analysed in 16 pDCL, four pDCL presenting an atypical phenotype (apDCL) and 113 non‐pDC – lymphoid or myeloid – acute leukaemia. CD123 was expressed at significantly higher levels in pDCL and apDCL. BDCA‐2 was expressed on 12/16 pDCL and on 2/4 apDCL, but was never detected in the 113 non‐pDC acute leukaemia cases. BDCA‐4 expression was found on 13/16 pDCL, but also in 12% of non‐pDC acute leukaemia. High levels of LILRA4 and TCL1A transcripts distinguished pDCL and apDCL from all other acute leukaemia (except B‐cell acute lymphoblastic leukaemia for TCL1A). We thus propose a diagnosis strategy, scoring first the CD4+ CD56+/− MPOneg cCD3neg cCD79aneg CD11cneg profile and then the CD123high, BDCA‐2 and BDCA‐4 expression. Atypical pDCL can be also identified this way and non‐pDC acute leukaemia excluded: this scoring strategy is useful for diagnosing pDCL and apDCL.

Multicentric study underlining the interest of adding CD5, CD7 and CD56 expression assessment to the flow cytometric Ogata score in myelodysplastic syndromes and myelodysplastic/myeloproliferative neoplasms

Although numerous recent publications have demonstrated interest in multiparameter flow cytometry in the investigation of myelodysplastic disorders, it is perceived by many laboratory hematologists as difficult and expensive, requiring a high level of expertise. We report a multicentric open real-life study aimed at evaluating the added value of the technically simple flow cytometry score described by the Ogata group for the diagnosis of myelodysplastic syndromes. A total of 652 patients were recruited prospectively in four different centers: 346 myelodysplastic syndromes, 53 myelodysplastic/myeloproliferative neoplasms, and 253 controls. The Ogata score was assessed using CD45 and CD34 staining, with the addition of CD10 and CD19. Moreover, labeling of CD5, CD7 and CD56 for the evaluation of myeloid progenitors and monocytes was tested on a subset of 294 patients. On the whole series, the specificity of Ogata score reached 89%. Respective sensitivities were 54% for low-risk myelodysplastic syndromes, 68% and 84% for type 1 and type 2 refractory anemia with excess of blasts, and 72% for myelodysplastic/myeloproliferative neoplasms. CD5 expression was poorly informative. When adding CD56 or CD7 labeling to the Ogata score, sensitivity rose to 66% for low-risk myelodysplastic syndromes, to 89% for myelodysplastic/myeloproliferative neoplasms and to 97% for refractory anemia with excess of blasts. This large multicenter study confirms the feasibility of Ogata scoring in routine flow cytometry diagnosis but highlights its poor sensitivity in low-risk myelodysplastic syndromes. The addition of CD7 and CD56 in flow cytometry panels improves the sensitivity but more sophisticated panels would be more informative.

Detection of functional platelet-activating factor receptors on leukemic B cells of chronic lymphocytic leukemic patients

Although platelet-activating factor receptors (PAF-R) are reported on normal B cells, few results are available concerning leukemic ones. We demonstrated functional PAF-R on cell and nuclear surfaces of leukemic B cells of chronic lymphocytic leukemic (CLL) patients. Analysis of 102 patients revealed dramatic differences for their membrane PAF-R expression, a result that might be related to their plasma IL-4 levels. In the light of the potent immunoregulatory role of PAF on B cell physiology, it is suggested that the presence or absence of PAF-R on leukemic B cells may profoundly affect their in vivo behavior.

Platelet-activating factor does not stimulate cAMP formation from immature forms of freshly isolated leukaemic blasts

To the Editor,PAF is a phospholipid mediator that sparks off awide range of immunoregulatory actions on maturehaematopoietic cells [1]. Intracellular and nuclearPAF-receptors (PAF-R) are reported [2–5]. Theybelong to the G-protein-coupled family. Studieshighlight the presence of PAF-R transcripts innormal haematopoietic CD34

Presence of membrane platelet-activating factor receptors on B cells of chronic B cell leukaemia patients.

Platelet-activating factor (PAF) is an inflammatory phospholipid molecule that acts in vitro on B cell activation, proliferation and immunoglobulin synthesis [1]. PAF acts through membrane PAF receptors (PAF-R) [2]. Recently, we have highlighted their presence on B cells of chronic lymphocytic leukaemia patients [3] and their virtual absence on leukaemic blasts of patients with acute B lymphoid leukaemia [4] suggesting that PAF-R might represent a marker of B cell differentiation and maturation. Taken together, these results lead us to examine for the presence of PAF-R in other mature B cell leukaemias. Blood was obtained from 42 untreated patients according to the Helsinki recommendations. Thirteen patients had mantle B cell lymphoma (6 men, 7 women, mean age 72 years), 15 had a villous or non-villous marginal zone B cell lymphoma (11 men, 4 women, mean age 74 years), 5 had follicular B cell lymphoma (2 men, 3 women, mean age 62 years), 5 had plasma cell leukaemia (2 men, 3 women, mean age 72 years) and 4 had prolymphocytic or prolymphocytoid B cell leukaemia (2 men, 2 women, mean age 77 years). PAF-R were investigated using flow cytometry as previously reported [3,4]. As shown in Fig. 1, B cells of patients with mantle B cell lymphoma, marginal zone B cell lymphoma, follicular lymphoma, prolymphocytic/prolymphocytoid leukaemia and plasma cell leukaemia expressed PAF-R. Using a cut off of 20% PAF-Rþ cells, PAF-R were found in 20% (1/5) of patients with follicular lymphoma, 50% (2/4) of patients with a prolymphocytic/prolymphocytoid leukaemia, 60% (3/5) of patients with a plasma cell leukaemia, 69% (9/13) of patients with a mantle cell lymphoma and 80% (12/15) of patients with a marginal zone B cell lymphoma. Fifty seven (15/26) and 68% (11/16) of patients with a k and a l chain expressed PAF-R, respectively, indicating that the nature of the light chain did not interfere with the presence or absence of membrane PAF-R. This short clinical study highlights PAF-R in several types of chronic (mature) B cell malignancies. It clearly strengthens the hypothesis that the expression of membrane PAF-R is a marker of B cell differentiation and maturation. While the physiological meaning of PAF-R on leukaemic B cells remains an open question, it

Harmonisation of full blood count reports, recommendations of the French-speaking cellular haematology group (GFHC)

Aims To propose recommendations related to the presentation, content and formulation of full blood count analysis reports. Methods Strong professional agreement among a group of experts from the French-Speaking Cellular Haematology Group (GFHC) was obtained. Results The following two proposals emerged from the consensus: (1) stratification of comments into three parts upon the discovery of an anomaly in blood cell analysis and (2) selection and/or redefinition of the terms recommended for designating the cell types found in normal and pathological peripheral blood. Conclusions The recommendations can help biologists who are currently undergoing the process of accreditation.