Figure 3

ADCC and trogocytosis in PBMCs from HER2+ breast cancer patients and healthy volunteers. SK-BR-3 cells were used as target cells in all experiments and PBMCs from HER2+ breast cancer patients (N = 3) and healthy volunteers (N = 3) were used as effector cells. The SK-BR-3 cells and PBMCs were co-cultured for 60 min in the trogocytosis assay and 90 min in the CD107a degranulation assay. Cell mixtures from the assays were stained with FITC-CD14, PE-CD56, APC-HER2, and PE-Cy5-CD107a antibodies and subjected to flow cytometry. A The trogocytosis assay was performed with an E:T cell ratio of 10:1 with and without trastuzumab (H0, without trastuzumab; H1, 1 μg/mL of trastuzumab). HER2 positivity represents the uptake of HER2 onto CD14⁺ and CD56⁺ effector cells. B The ADCC assay was performed with an E:T cell ratio of 10:1 with and without trastuzumab (H0, without trastuzumab; H1, 1 μg/mL of trastuzumab). CD107a positivity is indicative of target cancer cell cytotoxicity by CD14⁺ and CD56⁺ cells. C CD107a positivity on HER2⁺/CD14⁺, HER2⁻/CD14⁺, HER2⁺/CD56⁺, and HER2⁻/CD56⁺ cells is shown. D The trogocytosis assay was performed with an E:T cell ratio of 10:1 with and without trastuzumab (H0, without trastuzumab; H1, 1 μg/mL of trastuzumab). The level of HER2 expression on the trogocytosed SK-BR-3 cells is shown as the percent of HER2⁺ cells in each condition. *P < 0.005, **P < 0.05. All figures show the mean ± SD. Healthy volunteers are represented by open circles, squares, and triangles; patients are represented by closed circles, squares, and triangles.