Figure 2

Complement fixation by cetuximab. A, C1q binding to cetuximab was first evaluated in wells coated with different amounts of antibody and incubated with 1% NHS. A human IgG1 antibody able to fix C1q was used as a positive control. Monoclonal antibody OX24 and heat inactivated NHS (HI-NHS) were used as negative controls. Data shows mean ± SEM. B, Flow cytometry analysis of the binding of cetuximab to lung cancer cells (black line). A human IgG1 was used as an isotype control (grey line). C, Lung cancer cells were incubated with NHS and cetuximab. The binding of C1q to the Fc-region of cetuximab was analyzed by flow cytometry with the anti-human C1q antibody (black line) or an isotype control (grey line). Mean fluorescence intensities (MFI) are indicated.