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A surface-labeled lyophilized lymphocyte (sLL) preparation has been developed using human peripheral blood mononuclear cells prelabeled with a fluorescein isothiocyanate conjugated anti-CD4 monoclonal antibody. The sLL preparation is intended to be used as a reference material for CD4+ cell counting including the development of higher order reference measurement procedures and has been evaluated in the pilot study CCQM-P102. This study was conducted across 16 laboratories from eight countries to assess the ability of participants to quantify the CD4+ cell count of this reference material and to document cross-laboratory variability plus associated measurement uncertainties. Twelve different flow cytometer platforms were evaluated using a standard protocol that included calibration beads used to obtain quantitative measurements of CD4+ T cell counts. There was good overall cross-platform and counting method agreement with a grand mean of the laboratory calculated means of (301.7 ± 4.9) μL−1 CD4+ cells. Excluding outliers, greater than 90% of participant data agreed within ±15%. A major contribution to variation of sLL CD4+ cell counts was tube to tube variation of the calibration beads, amounting to an uncertainty of 3.6%. Variation due to preparative steps equated to an uncertainty of 2.6%. There was no reduction in variability when data files were centrally reanalyzed. Remaining variation was attributed to instrument specific differences. CD4+ cell counts obtained in CCQM-P102 are in excellent agreement and show the robustness of both the measurements and the data analysis and hence the suitability of sLL as a reference material for interlaboratory comparisons and external quality assessment. © 2015 The Authors. Published by Wiley Periodicals, Inc.

This report focuses on the characterization of CD4 expression level in terms of equivalent number of reference fluorophores (ERF). Twelve different flow cytometer platforms across sixteen laboratories were utilized in this study. As a first step the participants were asked to calibrate the fluorescein isothiocyanate (FITC) channel of each flow cytometer using commercially available calibration standard consisting of five populations of microspheres. Each population had an assigned value of equivalent fluorescein fluorophores (EFF denotes a special case of the generic term ERF with FITC as the reference fluorophore). The EFF values were assigned at the National Institute of Standards and Technology (NIST). A surface-labelled lyophilized cell preparation was provided by the National Institute of Biological Standards and Control (NIBSC), using human peripheral blood mononuclear cells (PBMC) pre-labeled with a FITC conjugated anti-CD4 monoclonal antibody. Three PBMC sample vials, provided to each participant, were used for the CD4 expression analysis. The PBMC are purported to have a fixed number of surface CD4 receptors. On the basis of the microsphere calibration, the EFF value of the PBMC samples was measured to characterize the population average CD4 expression level of the PBMC preparations. Both the results of data analysis performed by each participant and the results of centralized analysis of all participants' raw data are reported. Centralized analysis gave a mean EFF value of 22,300 and an uncertainty of 750, corresponding to 3.3% (level of confidence 68%) of the mean EFF value. The next step will entail the measurement of the ERF values of the lyophilized PBMC stained with labels for other fluorescence channels. The ultimate goal is to show that lyophilized PBMC is a suitable biological reference cell material for multicolor flow cytometry and that it can be used to present multicolor flow cytometry measurements in terms of ABC (antibodies bound per cell) units. V C 2015 International Society for Advancement of Cytometry Key terms surface labelled lyophilized PBMC; CD4 expression level; FITC; equivalent fluorescein fluorophore (EFF); quantitative flow cytometry; calibration; standard measurement procedure; measurement uncertainty; reference cell material CLUSTER of differentiation 4 (CD4) is a glycoprotein on the surface of T-helper cells, monocytes, macrophages and dendritic cells. As a co-receptor, CD4 amplifies the signal generated by the T cell receptor, which is essential for activation of many molecules involved in the signalling cascade of an activated T cell. The CD4-positive

Light scattering by single cells is widely applied for flow cytometric differentiation of cells. However, even for human red blood cells (RBCs), which can be modeled as homogeneous dielectric particles, the potential of light scattering is not yet fully exploited. We developed a dedicated flow cytometer to simultaneously observe the forward scattering cross section (FSC) of RBCs for orthogonal laser beams with incident wave vectors ì k 1 and ì k 2 . At a wavelength λ = 632.8 nm, bimodal distributions are observed in two-dimensional dot plots of FSC( ì k 1 ) vs. FSC( ì k 2 ), which result from the RBCs' random orientation around the direction of flow, as well as from the distributions of their size and their optical properties. Typically, signals of 7.5 × 10 4 RBCs were analyzed. We actively oriented the cells in the cytometer to prove that orientation is the main cause of bimodality. In addition, we studied the wavelength dependence of FSC( ì k 1 ) using λ = 413.1 nm, 457.9 nm, 488 nm and 632.8 nm, covering both weak and strong light absorption by the RBCs. Simulations of the light scattering by single RBCs were performed using the discrete dipole approximation (DDA) for a range of sizes, orientations and optical properties to obtain FSC distributions from RBC ensembles. Using the axisymmetric biconcave equilibrium shape of native RBCs, the experimentally observed distributions cannot be reproduced. If, however, an elongated shape model is employed that accounts for the stretching of the cell by hydrodynamic forces in the cytometer, the features of the strongly bimodal measured frequency distributions are reproduced by the simulation. Elongation ratios significantly greater than 1 in the range of 1.5 to 2.5 yield the best agreement between experiments and simulated data.

Shortly after the formal launch of the ICU project in the summer of 2017, representatives from the group works council of the GASAG group sat down with the trade union network Forum for the Social Forms of Technology, the FST, to start up an independent practical initiative to examine the topic of internal crowdsourcing to be implemented soon after. In 2018, a model works council agreement between the group works council and the management was agreed, henceforth framing the IC procedure in the GASAG group. The agreement is meant to serve as a template for the introduction of internal crowdsourcing in other companies and industries. A special feature of the agreement is the so-called ‘living’ group works council agreement. The following article analyses its significance and provides a translation by reproducing the agreement in its wording (This text is based on an original version in the German language that was published under the provisions of the Creative Commons at the URL: www.blog-zukunft-der-arbeit.de/betriebsraete-setzen-starken-innovationsimpuls-fuer-digitalen-aufbruch or www.blog-zukunft-der-arbeit.de.).