Cytomorphology of gynecologic specimens analyzed and sorted by two-parameter flow cytometry

The purpose of this study was to define the fluorescence and light scatter properties of the different cell types encountered in gynecologic specimens. Samples stained with Chromomycins A3 were analyzed on a laser-activated electronic cell sorter, and two-parameter histograms of the cell populations were generated from measurements of nuclear fluorescence and small angle light scatter. Cell populations with defined scatter and fluorescence ranges were sorted, stained by a modified Papanicolaou technique, and evaluated using conventional cytomorphologic criteria. We focused on determining which regions of the histogram corresponded with abnormal cells and cells defining specimen adequacy (columnar and metaplastic cells). Sorted cells corresponding with the main fluorescence region are single, benign, mononuclear cells. Relative proportions of the different types of cells in this region vary with light scatter. Leukocytes predominate at low scatter, mature squamous cells predominate at high scatter, and metaplastic and endocervical cells occur throughout this range. Cells sorted with higher values of nuclear fluorescence include dysplastic and malignant cells as well as benign cells occurring as groups, multinucleates, or with adherent leukocytes or bacteria. This study demonstrates that cytomorphology is a useful method for monitoring and interpreting flow cytometry data.