Characterization of in vitro migratory properties of anti-CD19 chimeric receptor-redirected CIK cells for their potential use in B-ALL immunotherapy

Objective Cytokine-induced killer (CIK) cells are ex vivo expanded cells enriched in CD3+CD56+ natural killer T (NKT) cells with major histocompatibility-unrestricted cytotoxicity against several tumoral targets, except B-lineage acute lymphoblastic leukemia (B-ALL). We redirected CIK cells cytotoxicity toward B-ALL with a chimeric receptor specific for the CD19 antigen and then explored if modified-CIK cells maintain the same chemotactic properties of freshly isolated NKT cells, whose trafficking machinery reflects their preferential localization into the sites of B-ALL infiltration. Material and Methods CIK cells were expanded ex vivo for 21 days and analyzed for expression of adhesion molecules and chemokine receptors regulating adhesion and homing toward leukemia-infiltrated tissues. CIK cells were then transduced with the anti-CD19-ζ-internal ribosomal entry site-green fluorescent protein retroviral vector and characterized for their cytotoxicity against B-ALL cells in a 51Cr-release assay and for their trafficking properties, including chemotactic activity, adhesion and transendothelial migration, and metalloproteases-dependent invasion of Matrigel. Results Similarly to freshly isolated NKT cells, CD49d and CD11a were highly expressed on CIK cells. Moreover, CIK cells expressed CXCR4, CCR6, and CCR7 (mean expression 72%, 60%, and 32%, respectively), presenting chemotactic activity toward their respective ligands. Anti-CD19 chimeric receptor-modified CIK cells became cytotoxic against B-ALL cells (mean lysis, 60%) and showed, after exposure to a CXCL12 gradient, high capacity to adhere and transmigrate through endothelial cells and to invade Matrigel. Conclusion The potential capacity to localize into leukemia-infiltrated tissues of anti-CD19 chimeric receptor-redirected CIK cells, together with their ability to efficiently kill B-ALL cells, suggests that modified-CIK cells represent a valuable tool for leukemia immunotherapy.