CD37CAR T cells are B-cell lineage specific. (A) Primary CD19⁺ B cells, CD3⁺ T cells, CD14⁺ monocytes, and CD56⁺ NK cells were isolated from healthy donor PBMCs and cocultured with effector mock T cells, CD19CAR T cells, or CD37CAR T cells generated from the same donors at E:T ratios of 1:2 and 1:5. Activated T cells, used as target, were generated via CD3/CD28 stimulation. Six hours after coculture, CD107a expression on effector T cells was assessed by flow cytometry. Data represent mean ± standard deviation of duplicates. (B) Bone marrow progenitor cells were cocultured with CD19CAR or CD37CAR autologous T cells from a healthy donor for 6 hours at an E:T ratio of 5:1. The cells were then plated in semisolid methylcellulose progenitor culture for 14 days and scored for the presence of red (CFU erythroid), white (CFU with granulocytes, macrophages, or cells of both lineages), and total (CFU with granulocyte, erythroid, macrophage, megakaryocyte) colonies. Data represent mean ± standard deviation of hexaplicates. Representative data from 1 of 3 experiments are shown, P > .5 for all data. Cytokine and chemokine secretion was measured by Bio-Plex assay of supernatants from T cells from 3 healthy donors, transfected with CD19CAR or CD37CAR and activated by coculture with BL-41 cells (C) or U2932 cells (D) for 24 hours at an E:T ratio of 1:2. Data represent mean ± standard deviation of triplicates. Data from 1 of 2 experiments are shown.