CD6 and neoplasm: Considering that the tumor cell lines do not express CD6, which excludes antibody-mediated cytotoxicity such as antibody-dependent cellular cytotoxicity (ADCC), and that itolizumab-mediated killing was only observed in those tumors expressing CD318, it was hypothesized that the increased cytotoxic capacity of PBMCs in co-cultures, in the presence of itolizumab, depends on the blockade of the interaction of CD6 with this ligands.