Cell partitioning in two-polymer aqueous phase systems and cell electrophoresis in aqueous polymer solutions. Red blood cells from different species.

A correlation, with some exceptions, between the partitioning behavior of red blood cells (RBCs) from different species in charge-sensitive dextran-poly(ethylene glycol) (PEG) aqueous phase systems and their relative electrophoretic mobilities (EPMs) in phosphate-buffered saline (PBS) has previously been reported. This relationship has now been further probed by carrying out RBC electrophoresis in media (i.e., dextran-rich bottom or PEG-rich top phases) more closely approximating the environment in which RBC partitioning takes place to see whether a better correlation would ensue. The ratios of viscosity-corrected EPMs of different species' RBCs in (diluted) dextran-rich or PEG-rich phases/EPMs of the respective species' RBCs in PBS differ for a number of species, and from each other, reflecting thereby differences in kind (i.e., dextran or PEG) and nature of polymer interaction with these RBCs. There is a general tendency for EPMs in any of the tested media to correlate with both the cells' relative partition ratios as well as with their relative EPMs in one of the other media. However, examination of the behavior of different species' RBCs taken two species at a time indicates that their relative EPMs in any two suspending media or in one suspending medium and partitioning often differ. Thus, both the cell partition ratio and the cell EPMs obtained in polymer media must, at least in some cases, reflect surface properties other than or in addition to the charge reflected by EPM measurements in PBS or saline. Cell electrophoresis in polymer solutions thereby provides an additional parameter for discriminating between surface properties of certain closely related cell populations.