Percoll density gradient centrifugation. (An improved method for the enrichment of lymphocyte subsets mediating different activities).

Lymphocyte fractions obtained by Percoll density gradient centrifugation were assayed for their cytotoxic activities both in NK and ADCC cytotoxic systems. Furthermore, the release of a mediator, platelet slowing factor from the same subsets, was evaluated. Different mitogens (phytohemagglutinin, concanavalin A and lipid A) have been used for this purpose. The maximum of cytotoxic activities was recovered in E+ cell-enriched fractions. On the other hand, lipid A was able to stimulate the PSF production from enriched B cells (fraction I); phytohemagglutinin induced the release of PSF from E+ fractions (II and III) and concanavalin A from fraction II only. Our results suggest that Percoll density gradient is a very reproducible method in obtaining lymphocyte subsets enriched in cells mediating either cytotoxic activities or lymphokine release.