Figure 4. Effects of methionine oxidation on the activation of FcγRIIa and FcγRIIIa by cetuximab.
(A) Binding affinities of t-BHP-treated cetuximab to EGFR, FcRn, FcγRIIa and FcγRIIIa were measured by an SPR analysis. Dissociation constant (KD) values are represented as mean ± SD (n = 3). *, p<0.05; **, p<0.01; ***, p<0.005; n.s, not significant. (B) Activation of FcγRIIa and FcγRIIIa by t-BHP-treated cetuximab was measured by an FcγR reporter assay using A431 cells as target cells. Methionine oxidation caused by t-BHP treatment dose-dependently decreased the activation of FcγRIIa (*, p<0.05; ***, p<0.005), but not that of FcγRIIIa (not significant).