ABSTRACT
The new Quality Control Program in Immunophenotyping for Central Europe (CEQUAL) was created in 1993. Its first formal send-around proficiency exercise, consisting of a stained stabilised preparation of leukocytes, took place in November 1993. Forty-one laboratories from Slovakia, Poland, Hungary, and the Czech Republic participated. Eighty-three percent of member laboratories returned results and list mode files. The results for each cell population were evaluated for central tendencies, variability, and overall distribution patterns. Extreme outliers were identified and list mode files reviewed for clues to the aberrerant values. When found these reasons were communicated back to member labs. When extreme outlier values were removed, all coefficient of variations (CVs) for lymphocyte populations were below 10%, except for NK cells, which had a CV of 14.8%. In future send-arounds, unstained and pathologic specimens will be used. This CEQUAL program is the first to function on such a broad international basis.
Subject(s)
CD4-Positive T-Lymphocytes/cytology , CD8-Positive T-Lymphocytes/cytology , Flow Cytometry , CD4-CD8 Ratio , Europe , Humans , International Cooperation , Multicenter Studies as Topic , Phenotype , Quality ControlABSTRACT
A device is described which makes it possible to count absolute particle (cell) numbers per volume by flow cytometry. It can easily by adapted to several types of flow cytometers, especially to the Coulter EPICS V and EPICS 750 series. A volume adapter has been installed in place of the normal sample handling system without any further modifications of the instrument or the data acquisition program. The adapter consists of a special pipette with two opto-electronic detectors for the beginning and end of the measuring period. These switch on/off a shutter for the illuminating laser beam so that acquisition of the data is controlled indirectly. Sample volumes of 50 microliters were measured at flow rates up to 10(3) particles/s. Calibration beads as well as blood cells were enumerated according to FALS (forward angle light scatter), to SSC (90 degrees light scatter), and to fluorescence parameters. The results were compared to the evaluation made on a Coulter counter or in a Neubauer chamber of a light microscope. Using a concentration of 1 x 10(5)-5 x 10(5) particles/ml, the absolute numbers of particles were determined with a high reproducibility and an estimated error rate of 2-5%.
Subject(s)
Cell Count/instrumentation , Flow Cytometry/instrumentation , Antibodies, Monoclonal/immunology , Antigens, Differentiation, T-Lymphocyte/immunology , CD2 Antigens , Electronics , Equipment Design , Fluorescein-5-isothiocyanate , Lasers , Microscopy , Microspheres , Receptors, Immunologic/immunology , Reproducibility of Results , T-Lymphocytes/immunologyABSTRACT
Isolated metaphase chromosomes of several fibroblastoid cell lines (Chinese hamster, Chinese hamster x human hybrid) were subjected to free flow electrophoresis (FFE) to study their electrophoretic mobility (EM). The morphology and stability of the chromosomes were unaffected by FFE as examined by cytogenetic methods and flow cytometry. The chromosomes of the complement all showed similar EM under most of the conditions applied. At neutral pH the EM of the chromosomes had the same sign as free DNA and about 2/3 of its magnitude. The variation of EM with buffer parameters such as ionic strength, valence of counterions, buffer capacity and dielectric constant of the solvent were investigated. Thermal denaturation increased the EM of the chromosomes by 20%. Partial denaturation might offer a possibility to separate or enrich large amounts of chromosomes by FFE.
