Figure 1.

IgA mediates higher tumor cell lysis than IgG with human neutrophils. (A–D) Specific lysis of tumor cells by isolated human neutrophils (E:T = 40:1) using a 4 h ⁵¹Cr release assay. Anti-CD20 Abs were used for Ramos and EL4-CD20, anti-HER2 Abs were used for SK-BR-3 and Ba/F3-HER2, anti-EGFR Abs were used for A431 and A1207 target cells. (A–C) Specific lysis of indicated target cells using a broad titration range of IgA and IgG antibodies. (D) Antibody concentrations were identical (10 μg/mL) for IgG and IgA antibodies against all target cells except for Ramos (13.3 μg/mL) and A1207 cells (1 μg/mL). Ctrl indicates condition without antibody (or 0.001 μg/mL IgG1-anti-CD20 for Ramos cells). One representative graph is shown for n = 4–6 independent experiments with different healthy donors. p < 0.001: ^***, p < 0.0001: ^****, unpaired Student's t test. (E) Stills from live cell microscopy of adhered A431-HER2 cells (calcein labeled) and neutrophils in the presence of 5 μg/mL anti-HER2 IgA2 or IgG (Trastuzumab) and TO-PRO-3 (red fluorescence), time in minutes, image acquisition every 30 s for 1.5 h.