Figure 4. Evaluation of donor-specific CDC.

Serum samples (12.5% final concentration) of four healthy donors D1 (A), D2 (B), D3 (C) and D4 (D) were analyzed using calcein-AM-based cytotoxicity assay as described in section “Materials and Methods”. Serial dilutions of 1.0 µg/ml ch14.18/CHO were used for CDC (closed circles). Rituximab served as a negative control (1 µg/ml; open triangles). To show GD₂-specific target cell lysis, samples were pre-incubated with excess of GD₂-mimicking anti-Id Ab ganglidiomab (5 µg/ml; closed squares). Data are shown as mean values ± SE of three independent experiments performed at least in triplicates.