PTX3-mediated increase of A fumigatus conidia phagocytosis depends on the alternative pathway of complement. (A) The phagocytosis assay was performed in the presence of 10% C1q-, C3-, C5-, or Factor B–depleted human serum (C1qDHS, C3DHS, C5DHS, and FBDHS) or C4-depleted guinea pig serum (C4DGS). Sera were reconstituted with the respective purified human proteins (C1q, C3, C4, C5, Factor B). (B) The phagocytosis assay was performed in the presence of C3, Factor B, Factor H, Factor D, or Factor I at the concentration present in 10% NHS. Results are paired PI values of independent donors in the absence or presence of recombinant PTX3. *P ≤ .05; **P < .01; ***P < .0001, Student paired t test.