Identification of lymphocyte subpopulations with a polymethine dye

Using the polymethine dye p-ethoxyphenyl-p-aminostyryl-1,3,3-trimethyl-3H-indolium chloride as an aqueous stain applied to specimens of peripheral blood or buffy coat fixed in FAA fixative, differential coloration of leukocytes was achieved using darkfield illumination. Neutrophils stained dark maroon and contained green granules, eosinophils contained bright blue granules, basophils revealed yellow and pink granules, and monocytes stained green with green and yellow vacuoles. In studies of purified lymphocyte subpopulations obtained in a cell sorter, T-helper cells stained red, T-suppressor cells were yellow orange, B-cells appeared yellow and often contained yellow annular structures in the cytoplasm, and natural killer (NK) cells stained green and contained large green granules. As a rapid screening technique for identification of T-helper and T-suppressor cells and their ratios in health and disease, the new polymethine stain may complement the more complex monoclonal antibody techniques for identification of these cells.