PTX3-mediated increase of A fumigatus conidia phagocytosis depends on CD32, which regulates CD11b activation. (A) The phagocytosis assay was performed in the presence of 10% NHS and anti-CD16 (LNK16) or anti-CD32 (AT10 or IV.3) blocking antibodies or control IgGs. Results are mean ± SEM of 3-5 pooled experiments. *P ≤ .05; Student paired t test. (B) FACS analysis of membrane and intracellular activated CD11b in permeabilized neutrophils defined as FSC-A^high/SSC-A^high, after incubation of whole blood with PTX3-opsonized conidia for 15 minutes, in the presence of F(ab′)2 blocking anti–human CD16 (3G8) and CD32 (7.3). The histogram shows 1 of 7 donors analyzed with similar results. (C) Ratio of activated and total CD11b MFI PE/APC in permeabilized cells after incubation for 15 minutes with conidia or PTX3-opsonized conidia in the presence of anti-CD16 (3G8) or anti-CD32 (IV.3) blocking antibodies.