An Extensive Quality Control and Quality Assurance (QC/QA) Program Significantly Improves Inter-Laboratory Concordance Rates of Flow-Cytometric Minimal Residual Disease Assessment in Acute Lymphoblastic Leukemia: An I-BFM-FLOW-Network Report.

Monitoring of minimal residual disease (MRD) by flow cytometry (FCM) is a powerful prognostic tool for predicting outcomes in acute lymphoblastic leukemia (ALL). To apply FCM-MRD in large, collaborative trials, dedicated laboratory staff must be educated to concordantly high levels of expertise and their performance quality should be continuously monitored. We sought to install a unique and comprehensive training and quality control (QC) program involving a large number of reference laboratories within the international Berlin-Frankfurt-Münster (I-BFM) consortium, in order to complement the standardization of the methodology with an educational component and persistent quality control measures. Our QC and quality assurance (QA) program is based on four major cornerstones: (i) a twinning maturation program, (ii) obligatory participation in external QA programs (spiked sample send around, United Kingdom National External Quality Assessment Service (UK NEQAS)), (iii) regular participation in list-mode-data (LMD) file ring trials (FCM data file send arounds), and (iv) surveys of independent data derived from trial results. We demonstrate that the training of laboratories using experienced twinning partners, along with continuous educational feedback significantly improves the performance of laboratories in detecting and quantifying MRD in pediatric ALL patients. Overall, our extensive education and quality control program improved inter-laboratory concordance rates of FCM-MRD assessments and ultimately led to a very high conformity of risk estimates in independent patient cohorts.

Transgene expression enhancement in T-lymphoma cell lines.

In transfection protocols, the expression levels of the transgene is important to define, still is difficult to obtain in certain cell lines such as those derived from T-lymphoma cells. In this study we evaluate transgene expression kinetics in the presence and absence of two well known transcription activators such as phorbol-12-myristate13-acetate (PMA) and Ionomicin (IO). Three murine T lymphoma cell lines (LBC, EL4 and BW5147) were transfected by electroporation using green fluorescent protein (GFP) as a reporter gene and analyzed by flow cytometry. Addition of PMA/IO resulted in a significant increase of the Mean Fluorescence Intensity but not in GFP-positive cell percentages, either in transient or stable transfected LBC and EL4 cells. Remarkable, BW5147 cells showed low GFP induction with a significant increment only in stable transfected cells. Our results demonstrated that CMV promoter activity can be enhanced in transfected lymphoma cells by PMA/IO suggesting that transgene expression levels can be optimized by means of the use of transcription activators.

Complete rejection of a T-cell lymphoma due to synergism of T-cell receptor costimulatory molecules, CD80, CD40L, and CD40.

The equal importance of the qualitative and quantitative characteristics of antigen presentation as well as the set of costimulatory signals provided by antigen presenting cells to T-cells in determining the outcome of T-cell responses at the time of antigen recognition is now clear. Moreover, an important function in innate mechanisms has been recently attributed to costimulatory molecules demonstrating their relevant role in different stages of immune response. In this paper, we demonstrated the ability of CD40L (CD154) and CD80 costimulatory molecules expression in a T-cell lymphoma to induce both T-cell dependent and independent immune responses leading to an important anti-tumor effect. CD40 expression by LBC cells enhanced only T-cell dependent anti-tumor immune response resulting in tumor rejection. Furthermore, this work represents the first report to describe complete tumor rejection after co-inoculation of lymphoma cells transfected with CD40L and CD80 in either presence or absence of CD40 expressing lymphoma cells. In addition, this synergistic effect resulted in long lasting immunity to parental tumor cells. Co-inoculation of tumor cells each genetically modified to express a different costimulatory molecule circumvents the need to co-transfect genetically unstable tumor cells and represents an option for those weakly or non-immunogenic tumors where either treatment alone proved to be inefficient. This strategy represents a promising approach for inducing anti-tumor immunity and provides a new rational design of cancer therapies.