UNCLEAVABLE CD16A PROMOTES ANTIBODY-DEPENDENT PHAGOCYTOSIS OF INDUCED PLURIPOTENT STEM CELL-DERIVED MACROPHAGES

Abstract

Macrophages have emerged as a promising cell type for cellular cancer immunotherapy due to its high penetrating capability, and ability to modulate tumor microenvironment. Although macrophages are highly resistant to genetic manipulation, overexpression of chimeric antigen receptor (CAR) has shown to improve its specificity and tumor-killing effect. Induced pluripotent stem cell is an attractive source for next-generation cellular immunotherapy due to it provide a platform for multiple genomes editing and scale-up manufacturing. CD16 is critical for antibody-dependent cell-mediated cytotoxicity of both NK- and T-cell types but the role in ADCC of macrophage remains unclear. In this study, we created human induced pluripotent stem cell (iPSC) line containing a mutant CD16 that is resistant to ADAM17 cleavage using CRISPR mediated genome editing technique. The iPSCs were then differentiated into iPSC-derived macrophages (iMacs), and CD16 expression was assessed using flow cytometry. The results demonstrated significantly higher levels of CD16 expression in non-cleavable CD16 iMacs compared to unmodified iMacs. Importantly, the engineered iMacs exhibited a significantly greater phagocytic activity (~50%) compared to normal iMacs (~36%) in co-culture experiments with a B-cell lymphoma cell line treated with anti-CD20 mAbs. These findings indicate that maintaining CD16 expression on iMacs contributes to enhancing their antibody-mediated antitumor function.