The fluorescence activated cell sorter (FACS) was used for measuring the uptake of the fluorescent fatty acid derivative U-(l-pyrene) dodecanoic acid (Pa) by human peripheral blood cells. The results indicate that blood cells differ widely in their ability to take up Pl2, with polymorphonuclear cells showing the greatest uptake, followed by lymphocytes, platelets, and RBCs. These differences in Pl2 uptake provide a potential additional parameter for differential cell counting. Using the ability of the FACS to "gate out" nonrelevant cells, it was possible to measure the rate of Pl2 uptake by each respective cell type even when admixed with other cells. Thus elaborate physical separation procedures could be avoided, and contaminating cells did not influence the results. Differences in Pl2 uptake were also utilized to separate blood cells into pure subpopulations of specific cell types.
Key terms: Fluorescence activated cell sorter, fatty acid derivativesA major obstacle in studying biological and biochemical properties of specific cells is the fact that, in vivo, cells are admixed with a variety of other cell types. For example, the study of hemopoietic cells is limited by the heterogeneity of a population consisting of cells belonging to several lineages that are at various stages of maturation. Analysis of such cells requires complete separation into discrete, homogenous subpopulations, since even a small contamination by cells that differ considerably in the property examined from the subpopulation studied may affect the results.We have demonstrated that the fluorescent, mediumchain fatty acid lZ-(l-pyrene) dodecanoic acid (P12) is effectively transported across the membranes of several cultured cell types and incorporated into their neutrallipids and phospholipids (10,ll). Using in vitro established leukemic cell lines, we have shown that cells of different hemopoietic lineages and stages of maturation differ in the rate and extent of PI2 uptake as well as in their metabolism of this acid (43). Recently, we have shown that the cellular uptake of P12 can be measured by the fluorescence activated cell sorter (FACS) (13,141, The present study describes the uptake of P12 by various cell types present in human peripheral blood and shows that blood cells differ widely in their ability to take up the compound. By taking advantage of the abilpossible to measure the rate of P12 uptake by each respective cell type, even when admixed with other cells. Thus elaborate separation procedures were avoided, and contaminating cells did not influence the results. Differences in P12-uptake were also utilized to separate blood cells into pure subpopulations of specific cell types.
MATERIALS AND METHODS
CellsPeripheral blood from normal individuals cells was collected in preservative-free heparin or citrate. Buffy coat cells were separated by mixing 2 volumes of blood with 1 volume of 1% dextran in saline (Pharmacia, Uppsala, Sweden) and allowing it to sediment at unit gravity for about 1 hour at room temperature. The cellcontai...