Anti-CD52/complement-dependent lysis is proportional to the surface density of the CD52 epitope.
DC subsets and their progenitors were compared for surface expression of CD52 and sensitivity to complement-dependent lysis by humanized anti-CD52. Filled bars indicate the MFI of CD52 expression, plotted against the left y-axis (note log10 scale). Empty bars, plotted against the right y-axis, represent the percentage of cells lysed after opsonization with an excess of humanized anti-CD52 (1 mg/mL alemtuzumab), thorough washing, and exposure either to 50% plasma without heat inactivation or the equivalent of commercial complement. Complement exposure was normally 1 hour at 37°C, but cellular resistance to lysis was also confirmed even after overnight incubation. Expression of CD52 and sensitivity to anti-CD52/complement-mediated lysis in vitro are strongly correlated, with the exception of CD34+ HPCs (see also MFI depicted in Figure 1). This graph summarizes 3 independent experiments, and error bars represent the SD of the triplicate means.
