In studies of phagocytosis and its consequences for cell activation, it is important to
distinguish those particulate stimuli which are completely ingested and internalized from
those which are only attached to phagocytic surfaces. Ingestion can be profoundly
influenced by both the type of opsonins on the surface of the stimulus and the expression
and activation of receptors on the phagocytes for these opsonins. We report a new
fluorescent assay which facilitates rapid and reproducible quantitation of attached versus …