Flow cytometric analysis of lymphomas and acute leukemias.

In summary, flow cytometry is highly applicable to the detection and classification of leukemias and lymphomas due to the ease with which single-cell suspensions may be made. Composite immunophenotypic analysis is essential for classifying leukemias once the disease is detected by traditional means. In contrast, in the detection of lymphoproliferative diseases, the composite immunophenotype is itself diagnostic of the disease process. Characterization of size, as measured by light scatter and by DNA ploidy and cell cycle analysis, contributes to the further subdivision of lymphoproliferative disorders. Specifically, small, monoclonal cells that are diploid with a synthetic fraction of 5% are characteristic of low-grade lymphomas. Admixtures of large and small cells wherein the large cells are monoclonal and the small cells are either monoclonal or heterogeneous may be seen in intermediate lymphomas. In this category, DNA ploidy is variable and the total synthetic fraction is usually between 5% and 15%. High-grade lymphomas, with the exception of the immunoblastic category, are usually of intermediate size, are diploid or near-diploid, and exhibit synthetic fractions greater than 15%. Interestingly, few reactive T cells are seen. Ongoing efforts to standardize procedures will eventually result in more widespread applicability together with improved understanding of the attributes and limitations of this technology. The most important consideration, however, is that the technology is useless in the absence of a working knowledge of the biology of the diseases to be characterized. Conversely, the complexity of flow cytometry is sufficient to warrant rigorous training of laboratory professionals in this field.