CD24 and CD44 expression by pleural effusion cells. Cells isolated from pleural effusions were analysed for their expression of CD44 and CD24 by flow cytometry using antibody clone G44-26 conjugated to fluorescein isothiocyanate to detect CD44 and using the ML5 antibody conjugated to phycoerythrin to detect CD24 (see Materials and methods). Control analyses were performed with an isotype-matched antibody. This is shown for the sample PE14 (Iso) along with the analysis with CD44 and CD24 antibodies (Test). For the other samples, the lines to form the quadrants were applied based on the analysis with the control antibody. The percentages in the right bottom quadrant refer to the CD44+ CD24low/- population. PE, pleural effusion.