1H11 generation and characterization. (A) A workflow schematic of 1H11 development. (B) 1H11 shows high binding affinity and specificity to recombinant CSP (rhCSP*) by kinetic binding assay and (C) in proteo ELISA. (D,E) Cell binding assays were performed to evaluate 1H11 binding to human and murine native CSP by incubating (D) human CSP+ OC cell lines, SKOV3 or OVCAR8, or (E) murine CSP+ cell line, Han14.3, with serial dilutions of 1H11 or IgG. (F,G) Antibody internalization was evaluated by incubating OVCAR8 cells with 1H11 or IgG for 30 min, then co-staining for markers of endocytosis, (F) EEA1 or (G) LAMP-1. Immunofluorescence imaging shows rapid internalization of 1H11 compared to IgG. Representative images are shown. Blue, DAPI; green, WGA; white, endosome markers (EEA1 or LAMP1); red, treatment condition (1H11 or IgG). Scale Bar = 25 µm. Errors bars indicate mean ± SEM.