A, Humanized 1B7 and 11E6 antibodies and high-titer P-IVIG were assessed for PTx binding by ELISA. An ELISA plate was coated with PTx, blocked, incubated with the indicated concentrations of P-IVIG (◆), hu1B7 (∘), or hu11E6 (■). B, Sandwich ELISA to assess simultaneous binding of 1B7 and 11E6. Each sample was run in duplicate and each assay repeated at least three times.