Enrichment of oncolytic cells for adoptive therapy using centrifugal elutriation.

We have shown that centrifugal elutriation (CE) can be used to obtain large numbers of peripheral blood lymphocytes enriched for natural killer (NK) cell activity. Lymphocytes distributed in fraction 3 (F3) were enriched 2.3 fold for large granular lymphocytes, LGL, and 1.8 fold for cells with CD16+ phenotype. Both unseparated and F3 cells proliferated and were activated following culture with interleukin-2 (IL-2), although the NK-enriched cells displayed superior cytolytic activity against tumor cell lines, as well as against fresh leukemic blasts. Comparison of the cell surface phenotype of long-term cultures indicated a significantly higher frequency of CD56+, CD3- and CD16+ NK cells, and a reduced content of CD3+ T cells in F3 populations. These results suggest that IL-2 activated NK-enriched CE-fractionated lymphocytes may be more effective than unseparated mononuclear cells for adoptive therapy purposes.