Cytokine Induced Killer Cells Can Kill Target through Antigen/TCR Dependent and Independent Mechanisms: New Clinical Perspectives of Utilisation

Abstract 3024 Poster Board II-1000 Cytokine induced killer (CIK) cells cultures can easily be obtained by stimulating PBMCs with monoclonal antibody anti-CD3 OKT3, IFNgamma and IL2. After 3-4 weeks at least 3 separate populations are present in the culture: CD3+/CD56-/CD8+ precursors (40.5 ± 19.9%), CD3-CD56+ NK cells (2.5 ± 1.5%) and CD3+/CD56+/CD8+ CIK cells (56.9 ± 21%) which show a T EMRA phenotype (Franceschetti et al., Exp Hematol. 37, 616-628, 2009). CIK cultures are currently used in allogeneic or autologous settings as potential anti-neoplastic effectors for adoptive transfer clinical approaches. We have further characterised the mechanism of target cell recognition and role of activating receptors and of lytic mediators in the cytotoxicity of purified CD3+/CD56+/CD8+ CIK cells. We have observed that CIK cells can kill targets through at least two distinct mechanisms: the first TCR-dependent and antigen-specific and the second non TCR-dependent. Indeed, upon TCR/CD3 crosslinking in CIK cells we observe ERK-1/2 phosphorylation, IFNgamma production (mean 32.6% of positive cells by intracellular staining) and TNFalpha production (mean 19.6%). CD3 ligation by OKT3 results in a significant increase over time in the percentage of CIK cells undergoing degranulation evaluated as CD107a positive cells (respectively 15.5 ± 2.2% at 60', 24.4 ± 1% at 120', 32,9 ± 8.7% at 180' and 34.2 ± 11.1% at 240'). CD3 ligation on CIK cells can induce cytotoxicity in a reverse Ab-dependent killing assay. Addition of OKT3 enhances also the cytotoxicity of CIK cells against K562 leukaemic target (from 16 ± 5% to 50 ± 4 %, E:T 10:1; p Disclosures No relevant conflicts of interest to declare.