Complement inhibits rituximab-mediated but not GA101-mediated NK-cell degranulation. (A) Expanded CIK cultures from normal donors and BJAB were mixed at 1:1 ratio for 3 hours with 10 or 100 μg/mL of rituximab or GA101 in complete medium (black columns), in the presence of 20% human serum (HS) with (thin striped columns) or without (open columns) 200 μg/mL blocking anti-C5 mAb eculizumab, heat-inactivated HS (thick striped columns), or 400 μg/mL IVIG (gray columns). Surface CD107a marker expression was determined using flow cytometry with gating on CD3⁻/CD56⁺ NK lymphocytes. Mean percentage of CD107a⁺/CD3⁻/CD56⁺ cells and SDs are shown (n = 2). (B) C3b/iC3b (top panels) or C3b/iC3b/C3dg deposition (bottom panels) on BJAB cell line was measured by direct immunofluorescence after addition of 100 μg/mL rituximab (left) or GA101 (right).