A flow cytometric procedure for the quantification of cell adhesion in complex mixtures of cells

We present a simple non-radioactive cytometry-based assay that permits the simultaneous quantitation of cell adhesion of distinct subsets of cells con tained in a mixture without any previous fractionation. The procedure is si mple and highly reproducible and has the advantage of confining the quantit ation of cell adhesion to live cells only. This new approach is based on co unting the absolute number of cells. This is done by adding known numbers o f distinguishable beads to the cell suspension and counting beads and cells in a cytometer. Quantitation of adhesion is accomplished by counting each subpopulation of cells before and after the adhesive process. To illustrate this methodology we determined adhesion of Ramos cells to monolayers of en dothelial cells and its inhibition by specific antibodies. Also, we determi ned adhesion to endothelial cells of B lymphocytes and subsets of T lymphoc ytes present in a preparation of unfractionated human mononuclear cells. Th e results presented here demonstrate that the new assay has the required pr operties to be used in the quantitation of cell adhesion. (C) 1999 Elsevier Science B.V. All rights reserved.