Mature moDCs are less sensitive than monocyte precursors and immature moDCs to anti-CD52/complement lysis, in proportion to their lower CD52 expression.

Cells were cultured in triplicate overnight in the presence of humanized anti-CD52 (alemtuzumab) and complement. The source of complement was either fresh human plasma or commercial complement in an equivalent concentration, ranging from 50% to 12.5% plasma in the culture medium. Percent lysis was calculated based on the remaining viable cells that excluded trypan blue on a direct hemacytometer count. Three experiments are summarized, and error bars represent the SD of the averaged triplicate means. MAb was used at 1 mg/mL in the experiments depicted, to confirm that resistant cells were insensitive even to anti-CD52 used in excess. Pairwise comparison of 3 groups performed using the Wilcoxon rank sum statistic yielded a Pbetween .2 and .33 for mature moDCs compared with immature moDCs or T cells in 3 concentrations of human plasma.