J6M0-mcMMAF promotes phagocytosis of MM cells by macrophages. (A) Long bone tissue sections from vehicle (A-G), iso-mcMMAF (4 mg/kg) (H-N), J6M0 (4 mg/kg) (a-g), J6M0-mcMMAF (0.4 mg/kg) (h-n), and J6M0-mcMMAF (4 mg/kg) (o-u) treated animals stained by H&E (A,H,a,h,o) and by IHC with human IgG (hIgG: B,I,b,i,p), J6M0 (C,J,c,j,q for BCMA), murine IgG (mIgG: D,K,d,k,r), murine anti-human CD138 antibody (E,L,e,l,s), rat IgG, and hematoxylin counterstain (rIgG: F,M,f,m,t), or F4/80 and hematoxylin counterstain (G,N,g,n,u for MΦ). Scale bar = 100 µm. ADCP at 4 hours was determined by flow cytometry using PKH67-labeled MM cells (B, MM1S; C, INA6, RPMI8226, H929) as targets and monocyte-derived macrophages as effector cells at an E:T ratio of 4:1. Experiments were done in triplicates. Percent phagocytosis was measured as the number of dual-positive (PKH67⁺CD11b⁺) cells divided by the total number of PKH67⁺ cells. Data shown are mean ± standard deviation from 2 independent experiments. *P < .02.