Figure 1.

(A) The structure of scdsFv version of HA22LR. The 2-chain disulfide- and peptide-(linker 1) linked Fv of an antibody targeting CD22 is combined with the domain III of native PE by the linker which bears Furin-cleavage site (linker 2) to create an immunotoxin. The Fv portion sequence is shown. Residue numbering is based on the Kabat numbering scheme.²² The CDR regions are defined according to Kabat et al. (underlined) and IMGT23 (boldface). Alanine-scanned CDR residues are shown in red. (B) Activities of dsFv-form (circles and dotted line) and scdsFv-form (squares and solid line) of HA22-LR on CD22-positive cells. The cytotoxicity was measured by WST-8 in triplicate 3 times. Typical cytotoxic curves are shown. Data are expressed as the mean ± SD. IT, immunotoxin.