Binding affinity of hFcγRs for IgG subclasses. (A) Real-time surface plasmon resonance sensorgrams and affinity constants (×10⁵ M⁻¹) were determined from SPR analysis. The standard deviation of the affinity constant (K_A) determination is indicated. n.m. indicates not measurable (ie, no detectable binding). (B) The affinity constants calculated in panel A are plotted against IgG subclasses. Data correspond to 1 experiment per interaction tested, which is representative of 2 to 6 independent experiments that gave similar results.