Fig. 5

CD74 expression remains on CD33+ myeloid subset of normal PBMCs. A CD74 antigen density on MCL cell (Table 1) was significantly higher than PBMCs from healthy blood donors, while no statistically significance between PBMCs and negative control SUDHL-1 was found. B Histogram plots of CD74 expression on CD33+ and CD33− PBMCs (shaded gray) compared to the isotype staining control (dotted line). CD74 densities on CD33+ and CD33− PBMCs were summarized from 3 independent donors (right). C Specific lysis of normal CD33+ cells when used as target cells for 42105-74bbz CAR-T cells. Mino cells were used as a positive control target. D CD74 expression on CD33+CD14+ monocyte (shaded gray) compared to the isotype staining control (dotted line). A summary of CD74 density on monocytes from 3 independent donors was plotted (right). E Susceptibility of monocytes to 42105-74bbz CAR-T cells (white) and UTT (black). F A subset of CD33−CD3+CD4+ T cells, CD33−CD3+CD8+ T cells, CD33−CD3−HLA-DR+CD19+ B cells and CD33−CD3−CD56+ NK cells expressed CD74. Data are from one representative of three independent experiments. CD74 densities on B cells, CD4+ T cells, CD8+ T cells and NK cells were all below 10,000 molecules per cell. Numbers indicate the median molecules per cell. Data are from three independent donors (bottom). G Susceptibility of resting and activated T/B cells to 42105-74bbz CAR-T cells (white) and UTT cells (black). Results are mean ± S.E.M. from three independent experiments. * p < 0.05; ** p < 0.01; ***p < 0.001. H 42105-74bbz CAR-T cells did not deplete normal immune cells. Autologous 42105-74bbz CAR-T cell number peaked on Day 18 post CAR-T cell injection in the humanized NSG mice. The absolute numbers of 74bbz CAR-T cell in these mice are plotted over time in different colors. I And there were no significant changes on the absolute cell numbers of circulating B cells, monocytes, G-MDSC, M-MDSC and NK cells measured on the same day. All human cells were identified by human CD45+. B: CD33−CD19+; Monocyte: LIN−CD45+CD11b+CD33+CD14+; G-MDSC: LIN−CD11b+CD33+CD14−HLA-DR−; M-MDSC: LIN−CD11b+CD33+CD14+HLA-DR−; NK: CD33−CD3−CD56+. Mice received either UTT cells (red, n = 5) and 42105-74bbz (blue, n = 7). Bars show the median cell number