Methodological aspects of minimal residual disease assessment by flow cytometry in acute lymphoblastic leukemia: A French multicenter study.

Background: Minimal residual disease (MRD) assessment provides a powerful prognostic factor for therapeutic stratification in acute lymphoblastic leukemia (ALL). Multiparameter flow cytometry (MFC) has the potential for a rapid and sensitive identification of high risk patients. Our group has previously published that MRD levels analyzed by clone specific Ig/TcR-QPCR and MFC were concordant at a sensitivity of 10-4 . Here we report the MFC methodological aspects from this multi-center experience. Methods: MRD was assessed by MFC in 1030 follow-up samples from 265 pediatric and adult patients with de novo ALL treated in the FRALLE, EORTC or GRALL clinical trials. MRD assessment as applied by the eight participating MFC laboratories is described in detail regarding cell preparation, leukemia-associated immunophenotype (LAIP) markers and data analysis. Samples were obtained from bone marrow (BM) and peripheral blood (PB). Immunostaining was performed after erythrocyte lysis or Ficoll enrichment. Results: This study confirms the applicability of MFC-based MRD assessment in 97% of patients with ALL at the 10-4 cut-off. MRD values after Ficoll enrichment and erythrocyte lysis were found comparable. Higher MRD values were obtained in BM than in PB, especially for B-lineage ALL. Conclusions: Measurement of MRD by MFC at the 10-4 cut-off is applicable within a few hours for almost all patients and using a comparable analytical strategy allows for multicenter collaborative studies. The method can be introduced in a strategy aimed at defining the risk of failure of patients with childhood or adult ALL. © 2014 Clinical Cytometry Society.

Potent and multiple regulatory actions of microglial glucocorticoid receptors during CNS inflammation.

In CNS, glucocorticoids (GCs) activate both GC receptor (GR) and mineralocorticoid receptor (MR), whereas GR is widely expressed, the expression of MR is restricted. However, both are present in the microglia, the resident macrophages of the brain and their activation can lead to pro- or anti-inflammatory effects. We have therefore addressed the specific functions of GR in microglia. In mice lacking GR in macrophages/microglia and in the absence of modifications in MR expression, intraparenchymal injection of lipopolysaccharide (LPS) activating Toll-like receptor 4 signaling pathway resulted in exacerbated cellular lesion, neuronal and axonal damage. Global inhibition of GR by RU486 pre-treatment revealed that microglial GR is the principal mediator preventing neuronal degeneration triggered by lipopolysaccharide (LPS) and contributes with GRs of other cell types to the protection of non-neuronal cells. In vivo and in vitro data show GR functions in microglial differentiation, proliferation and motility. Interestingly, microglial GR also abolishes the LPS-induced delayed outward rectifier currents by downregulating Kv1.3 expression known to control microglia proliferation and oxygen radical production. Analysis of GR transcriptional function revealed its powerful negative control of pro-inflammatory effectors as well as upstream inflammatory activators. Finally, we analyzed the role of GR in chronic unpredictable mild stress and aging, both known to prime or sensitize microglia in vivo. We found that microglial GR suppresses rather than mediates the deleterious effects of stress or aging on neuronal survival. Overall, the results show that microglial GR acts on several key processes limiting pro-inflammatory actions of activated microglia.

Flow cytometry and IG/TCR quantitative PCR for minimal residual disease quantitation in acute lymphoblastic leukemia: a French multicenter prospective study on behalf of the FRALLE, EORTC and GRAALL.

Minimal residual disease (MRD) quantification is widely used for therapeutic stratification in pediatric acute lymphoblastic leukemia (ALL). A robust, reproducible, sensitivity of at least 0.01% has been achieved for IG/TCR clonal rearrangements using allele-specific quantitative PCR (IG/TCR-QPCR) within the EuroMRD consortium. Whether multiparameter flow cytometry (MFC) can reach such inter-center performance in ALL MRD monitoring remains unclear. In a multicenter study, MRD was measured prospectively on 598 follow-up bone marrow samples from 102 high-risk children and 136 adult ALL patients, using IG/TCR-QPCR and 4/5 color MFC. At diagnosis, all 238 patients (100%) had at least one suitable MRD marker with 0.01% sensitivity, including 205/238 samples (86%) by using IG/TCR-QPCR and 223/238 samples (94%) by using MFC. QPCR and MFC were evaluable in 495/598 (83%) samples. Qualitative results (<0.01% or ≥0.01%) concurred in 96% of samples and overall positivity (including <0.01% and nonquantifiable positivity) was concurrent in 84%. MRD values ≥0.01% correlated highly (r(2)=0.87) and 69% clustered within half-a-log(10). QPCR and MFC can therefore be comparable if properly standardized, and are highly complementary. MFC strategies will benefit from a concerted approach, as does molecular MRD monitoring, and will contribute significantly to the achievement of 100% MRD informativity in adult and pediatric ALL.

Interdigitating cells sarcoma: occurrence during incomplete remission of a lymphoblastic lymphoma.

The authors report the successive occurrence of an interdigitating-cell sarcoma and a lymphoblastic lymphoma in an 8-year old child. The observation is documented by immunophenotype and genotype. The link between the two malignancies is discussed.