PTX3 does not influence the complement regulatory activities of C4BP.

<p>(A) Fluid phase C4BP cofactor assay. C4b was incubated with factor I (FI), C4BP and PTX3 in the indicated combinations. Samples were subjected to 10% SDS-PAGE under reducing conditions, transferred to nitrocellulose membrane, and C4b cleavage was detected by Western blot using a C4 antiserum. The C4b chains and the α′-chain cleavage product (α′15) are indicated on the right. One representative of three experiments is shown. (B) Solid phase C4BP cofactor assay. C4BP was added to wells coated with BSA, recombinant PTX3 or protein S. After washing, C4b and factor I were added at 37°C for 30 min, and C4b cleavage was analyzed from the supernatants by Western blot as described above. A representative experiment out of three is shown.