DE-treated sCJD-PrP^Sc is transported across Caco-2 epithelial cells. An aliquot of mock-treated, PK-treated, or DE-treated NH or CJDH was added to the AP chamber of Caco-2 monolayers, and PrP transported to the BL chamber was estimated after an overnight incubation. A, Immunoblotting of proteins from the AP and BL media with 3F4 shows no detectable PrP signal in the BL chamber of cells exposed to mock-treated (lanes 2, 3), PK-treated (lanes 4, 5), or DE-treated (lanes 6-9) NH. B, In contrast, a significant PrP signal is detected in the BL chamber of cells exposed to mock-treated (lanes 11, 12), PK-treated (lanes 13, 14), or DE-treated (lanes 15-18) CJDH. PrP peptide 106-126 (Tx-pep) is not transported to the BL chamber when mixed with either DE-treated NH (A; lanes 8, 9, arrowhead) or DE-treated CJDH (B; lanes 17, 18, arrowhead). Lanes 1 and 10 show PrP reactivity in the starting NH and CJDH samples, respectively. C, Measurement of total raw density of PrP signal indicates minimal transport of PrP from mock-treated NH. In PK-treated and DE-treated NH samples, as expected, minimal PrP signal is detected. In contrast, a prominent PrP signal is detected in the AP and BL chambers of monolayers exposed to similarly treated CJDH samples (lane numbers correspond to samples in A and B). D, Quantitative estimation shows transport of 14, 8.5, and 42% of PrP from the AP chamber to the BL chamber from mock-treated, PK-treated, and DE-treated CJDH, respectively. Transport of ³H-inulin was <0.01%/cm²/min before and after the completion of each experiment. The error bar represents the mean ± SD of four experiments. p < 0.01.