Fig. 6

Upregulation of CD38 by ATRA in lymphoid cancer cells. A CD38 expression in the CD38^low cell lines with or without ATRA treatment by flow cytometry. Jurkat, SP-53, or KMS-12 cells were treated with vehicle or ATRA with indicated final concentration for 48 or 96 h; the fold change of median fluorescence intensity (MFI) of CD38 in each cell line was blotted. B mRNA levels of CD38 in Jurkat, SP-53, or KMS-12 with or without treatment of ATRA with indicated concentration for 24 h. C The CD38 expression levels were evaluated by immunoblotting. NHL cell lines (SP-53, Granta-519, Mino, or WSU) were treated with ATRA (10 nM) for 48 h. D ADCC reporter cells responses to daratumumab were dependent on CD38 levels. SP-53 cells were pre-treated with ATRA (10 nM) for 48 h, followed by the ADCC reporter assay using Jurkat/NFAT-Luc/FcγRIIIa effector cells. E ATRA enhanced CD38-based ADCC or CAR T cell cytotoxicity in vitro. In the left panel, SP-53 cells were pre-treated with ATRA (10 nM) for 48 h followed by the treatment with daratumumab and IgG1 isotype antibody with PBMCs for 6 h; in the right panel, the cytotoxic activity of CD38-CAR T cells was measured co-culturing with SP-53 cells with or without ATRA (10 nM) pre-treatment for 6 h. F Secretion of IFN- γ, TNF- α, and perforin from T cells by ELISA. Assays were performed uisng supernatants obtained after a 20-h co-culture of T cells (CD38-CAR T cells and control T cells) and SP-53 cells with or without ATRA pre-treatment at a 2:1 E:T ratio