The aim of this study was therefore to address the cell diversity of circulating primary effector cytotoxic cells in thirty (30) healthy individuals, in the context of ADCC induced with trastuzumab using a HER2/neu-expressing breast cancer cell line (58–60), and to determine the key variables of ADCC and their relation with the structural and functional status of the cytotoxic cells. Here, ERBB2 is linked to breast cancer.