Cell surface expression of CD38, CD59, CD55 and CDC induction by CD38-specific hcAbs. (A) Cell surface expression of CD38 by human lymphoma cell lines (CA46, Daudi, LP-1) before and after transduction with GFP/luciferase. Non-transduced and GFP/luciferase-transduced cells were stained with Alexa647-conjugated MU1067-hcAb and analyzed by flow cytometry. Dot plots were overlaid for direct comparison of CD38 expression levels by non-transduced parental cells (GFP-) and GFP/luciferase-transduced cells (GFP+). (B) Cell surface expression of CD55 and CD59 by CA46, Daudi, and LP-1 cells before and after transduction with GFP/luciferase. (C) CA46, Daudi, and LP-1 cells were incubated for 60 min at 37°C with CD38-specific heavy chain antibodies WF211-hcAb, MU1067-hcAb, JK36-hcAb, isotype control (l-15-hcAb), or daratumumab in the presence of 15% pooled human serum as source of complement. The same pooled serum pretreated for 30 min at 56°C (inactivated serum) was used as control. Cells were then stained with propidium iodide and analyzed by flow cytometry to determine the percentage of lysed cells. Epitope specificities of CD38-specific antibodies are indicated in parentheses. Data represent mean ± SD from three independent experiments.