Interactive data analysis for evaluation of B-cell neoplasia by flow cytometry

DNA content measurement for DNA ploidy and cell cycle analysis

This unit presents the most common methods of DNA content analysis. The techniques differ primarily in the mode of cell permeabilization (detergents versus prefixation with alcohol) and composition of the stain solution. Protocols are given for analysis of fixed cells, tissue samples, live cells (for subsequent sorting and culture), archival paraffin-embedded tissue, and apoptotic cells.

Induction of apoptosis in human T-cells by organomercuric compounds: a flow cytometric analysis

Although several lines of investigation demonstrate that many heavy metals are cytotoxic to host defense cells, the mechanism of killing is poorly understood. The major focus of this investigation was to determine if organic mercuric compounds kill human lymphocytes by inducing the cells to undergo apoptosis and to evaluate possible flow cytometric systems for assessing cell death. T-cells were exposed to 0.6-5 microM MeHgCl, EtHgCl, or PhHgCl for up to 24 hr and then analyzed by flow cytometry. Mercury-treated cells exhibited increased Hoechst 33258 and 33342 fluorescence while maintaining their ability to exclude the vital stain 7-AAD. Furthermore, T-cells exposed to mercury exhibited changes in light scatter patterns that included decreased forward light scatter and increased side scatter. The light scatter and fluorescent changes were consistent with changes that cells display during apoptosis. To further evaluate cell death and to distinguish between apoptosis and necrosis, merocyanine 540 staining and annexin V binding to the plasma membrane as well as DNA fragmentation were assessed. Mercury-treated cells exhibited increased merocyanine 540 fluorescence and annexin V binding along with changes in nuclear morphology consistent with the notion of apoptosis. Conventional agarose gel electrophoresis failed to demonstrate low-molecular-weight DNA bands; however, when probed by flow cytometry using both nick translation and a modified TUNEL assay, patterns consistent with nuclear fragmentation were evident. We noted that the percentage of T-cells undergoing apoptosis was dependent upon the amount of serum present in the medium; as serum concentrations were increased from 0 to 10%, cell death declined. Apoptosis (33%) was observed within 1 hr of exposure to MeHgCl; maximum cell death (67%) occurred after 24 hr exposure. Induction of apoptosis was dependent on the mercury concentration and independent of the hydrophobicity of the mercury ligand. Finally, we assessed mercury-dependent apoptosis in activated T-cells. When treated with mitogen, mercury failed to induce apoptosis in these cells. Indeed, there was no evidence of either apoptosis nor necrosis in these populations. It was concluded that the activation process prevented development of a metabolic state that was required for induction of apoptogenic genes.

Laboratory practices in reporting flow cytometry phenotyping results for leukemia/lymphoma specimens: results of a survey

Laboratory directors who routinely utilize flow cytometry for at least part of their diagnostic evaluations in leukemias or lymphomas were surveyed by mail. The survey consisted of 12 questions about the flow cytometry procedures used by the laboratory in evaluating leukemias and lymphomas and on the format and content of their official report. It also requested an example of a typical leukemia/lymphoma report and solicited write-in comments about additional important aspects of using flow cytometry to evaluate leukemia and lymphomas not covered by the questionnaire. The goal of the survey, which was sponsored by the Clinical Cytometry Society (CCS), was to document what directors of flow cytometry laboratories currently consider to be the appropriate contents of a clinical leukemia/lymphoma phenotyping analysis and in what manner and detail they report such flow cytometry results to clinicians. The survey indicated that a large number of markers are routinely evaluated to phenotype leukemias (mean = 19) and lymphomas (mean = 16). Light scatter gating, using CD45/14 to monitor the gate selected, is currently employed by a 2:1 ratio over the next most population gating strategy (CD45 vs. 90 degrees LS). Peripheral blood, bone marrow, and lymphoid tissue constitute the majority of clinical specimens evaluated for leukemia and/or lymphoma. Two-color analysis, primarily for surface markers, is currently the standard method for flow cytometry measurements in routine diagnostic studies of leukemia and lymphoma. The official flow cytometry laboratory report is most commonly an individual-lab-generated, paper report form. A discussion of the potential benefits that might result from the development of improved computerized reporting software and from the increased use of antibody-defined, lineage gating is offered. A composite report format is presented that demonstrates the flow measurements and quality control data included in the best of the example clinical reports submitted as part of the survey and considered important by a majority of our survey respondents. The example report is intended to be a basis for further discussion within the flow cytometry community on whether minimum reporting standards for leukemia and/or lymphoma flow cytometry results can and should be developed.