Settling-time dependence of rat bone marrow cell partition and counter-current distribution in charge-sensitive aqueous two-phase systems. Relationship with the cell partitioning mechanism.

Differences in the settling-time dependence of single and multiple cell partitions have been found between heterogeneous (bone marrow cells) and homogeneous (erythrocytes) populations when using charge-sensitive dextran-poly(ethylene glycol) aqueous two-phase systems. The cell populations were partitioned using both single test-tube experiments and multiple thin-layer counter-current distribution. Lengthening the settling time, to favour phase separation, and decreasing the upper phase volume are more effective in fractionation by the counter-current distribution of heterogeneous cell populations than increasing the interfacial tension, although all three were employed to speed phase settling. On the basis of these results, the original cell partitioning mechanism proposed for non-charge-sensitive systems has been extended to charge-sensitive systems.