Cells on microspheres: a new technique for flow cytometric analysis of adherent cells.

Technical problems have previously prevented the application of fluorescence activated cell sorting to the study of adherent cell populations. We have developed a procedure for attachment of human monocyte-macrophages to 14-20 micrometer microspheres. These adherent cells on microspheres retained phagocytic capacity, could be stained for cell surface antigens using indirect immunofluorescence, and could be maintained in long-term culture. They could be examined and sorted on a fluorescence activated cell sorter while still in the adherent state. This technique facilitates the flow cytometric study of adherent cells and permits the isolation of subpopulations of these cells.