The predominant role of CD32(a) was confirmed by measuring the sADRB (A, C, and E) and mADRB (B, D, and F) in a 60-min kinetic window using CD16(b)-deficient PMNs, which were added untreated (filled symbols; A and B) or treated with Pi-PLC (open symbols; C and D) or with the CD32(a)-blocking antibody (half-filled symbols; E and F). The reactivities of PMNs were measured against SIP 5 (circles), the SIP-pool (squares), and one NIP (triangles) as representative examples. The data represent the mean ± range of one experiment using CD16-deficient PMNs from one donor in technical duplicates. (A and B) Luminescence intensities were normalized to the reactivity of SIP 5 in each assay and therefore, are presented in arbitrary units. (C and D) The residual percentages compared with the respective kinetics without Pi-PLC treatment are shown. (E and F) The residual percentages compared with the respective kinetics without blocking of CD32(a) are depicted.