Effects of alemtuzumab upon human AML. (A) Surface CD52 is minimally expressed on human AML cell lines MOLM13, MOLM14, MV4-11, THP-1, and U937 by FC analysis. Comparably bright CD52 expression is observed on normal human T cells (untransduced) and transduced CART123 cells used in subsequent in vivo experiments. (B) Coculture of MOLM14 cells with alemtuzumab and 15% complement (as in Figure 1) for 72 hours does not impair in vitro leukemia proliferation, as measured by viable cell counting with trypan blue exclusion. Each condition was performed in triplicate. Data points demonstrate mean cell count with standard error of the mean. (C) Histopathologic analyses of NSG mice treated with 1 dose of 1 mg/kg or 5 mg/kg alemtuzumab demonstrate no effect of alemtuzumab upon normal murine hematopoietic tissues (left panels) or upon human AML in NSG mice engrafted with MOLM14 (right panels). Images are hematoxylin and eosin–stained tissue sections from embedded paraffin blocks. Slides were scanned at ×20 magnification with an Aperio Scanscope CS-O slide scanner with visualization via the Aperio Image Analysis Toolkit (Leica Biosystems). ns, not significant by analysis of variance. PBS, phosphate-buffered saline.