Abstract
Background aims. Interleukin (IL)-15 and fms-like tyrosine kinase-3 (FLT-3) are crucial factors for the development of human and murine natural killer (NK) cells. Previously, we have demonstrated significant ex vivo expansion and activation of unrelated cord blood (UCB) NK cells with an antibody/cytokine cocktail consisting of anti-CD3 + IL-2 + IL-12 + IL-7 and anti-CD3 + IL-2 + IL-12 + IL-18. Methods. In the current experiments, we investigated the effects of short-term culture with anti-CD3 + IL-2 + FLT-3 + IL-15 on cord blood (CB) NK cell and NK-cell subset expansion and function. CB mononuclear cells were cultured for 48 h in AIM-V media or AIM-V + IL-2 (5 ng/mL) + anti-CD3 (50 ng/mL) + FLT-3 (50 ng/mL) ± escalating doses of IL-15 (1, 10 or 100 ng/mL). Flow cytometric analysis was performed using various fluorescent-conjugated monoclonal antibodies. In vitro cytotoxicity was determined with a standard europium assay against K562 and Daudi cells. Results. There was a 4.8-fold significant increase in NK-cell population (CD3−/16+/56+; P < 0.03), 21-fold significant increase in CD3−/56+/158a+ (KIR2DL1/S1; P < 0.002), 46-fold significant increase in CD3−/56+/158b+ (KIR2DL1/S2; P < 0.002) and 11.5-fold significant increase in CD3−/56+/NKB1+ (KIR3DL1; P < 0.01). We also noted a significant increase in both NK and lymphokine-activated killer (LAK) cytotoxicity with IL-2 + anti-CD3 + FLT-3 + IL-15 (100 ng/mL) compared with IL-2 + anti-CD3 + FLT-3 and media alone against K562 (P < 0.01) and Daudi (P < 0.001), respectively. Conclusions. We have demonstrated a significant increase in UCB NK cells and NK cells expressing a variety of killer immunoglobulin-like receptor (KIR) receptors after short-term culture with anti-CD3, IL-2, FLT-3 and IL-15. Furthermore, there was a significant increase in in vitro NK/LAK cell cytotoxicity.
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Acknowledgments
The authors would like to thank Lauren Harrison, RN, for her editorial assistance in the preparation of this manuscript.
This work was supported in part by a grant from the Pediatric Cancer Research Foundation, Marisa Fund, Brittany Barron Fund, Paul Luisa Foundation, Sonia Scaramella Fund, Swim Across America Foundation and Dreaming for Discovery and Cure.
Disclosure of interest: The authors have no conflict of interest to disclose.