Antibody-mediated inhibition of ricin binding to the surface of THP-1 cells.

aFITC-ricin (46 nM) was incubated with lactose or indicated antibodies for 30 min before being applied to THP-1 cells and then subjected to flow cytometry, as described in Materials and Methods. The percent (%) inhibition of ricin binding was calculated by dividing the experimental geometric mean fluorescence intensity (MFI) by the control (FITC-ricin only) geometric MFI and then multiplying by 100.