Prelytic stimulation of target and effector cells following conjugation as measured by intracellular fluorescein fluorescence polarization

The aim of the present study was to detect prelytic intracellular changes induced in target and effector cells following their conjugation at room temperature. Changes in the cytoplasmic matrix were measured by means of intracellular fluorescein fluorescence polarization (IFFP) using the Cellscan apparatus. Both natural killer and lymphocyte activated killer cells were used as effector cells, while K562 and Daudi cell lines were used as targets. The results show that following their conjugation, both the effector and the target cells show significant reductions (> 10%) in IFFP values. Changes in IFFP were induced by specific interaction and only between viable cells. No evidence of fluorescein transfer from a stained cell to its nonstained counterpart was found. To the best of our knowledge, this is the first time that effector-target interaction is monitored on an individual cell basis within a population, by means of IFFP measurements. In addition, in order to explain the physical phenomena, measurements of physical parameters which might affect the IFFP, such as changes in osmolality and pH, were performed and discussed.