FIGURE 6.

Inhibition of ricin binding to cell surfaces by heterodimeric and homdimeric VHHs. VHH heterodimers and homodimers were mixed with FITC-labeled ricin prior to being applied to THP-1 cells in solution and then subjected to flow cytometry, as described under “Experimental Procedures.” The percent binding was normalized to ricin only treated cells (solid black bar). Lactose was used as a known inhibitor of ricin attachment (gray bar). Experiments were repeated three independent times and the bar graphs represent each treatment mean ± S.D., values are shown by each corresponding treatment. One-way analysis of variance was used to compare the ricin control to each antibody treatment (**, p < 0.01; ***, p < 0.001).