Protective effects of anti-ricin A-chain antibodies delivered intracellularly against ricin-induced cytotoxicity

Figure 4 Protective effects of MTS-conjugated dgA Ab for post-exposure treatment of ricin-induced cytotoxicity. RAW264.7 cells were exposed to ricin (100 ng/mL) for 1 h, 2 h or 4 h to allow time for the toxin to internalize into cells. After a short exposure, cells were washed 3 times with PBS to remove extracellular ricin. Then MTS-conjugated dgA antibody or naked (unconjugated) dgA Ab (1 μg/well) was added and incubated for another 24 h and cell viability was quantitated by the MTT assay. Naked dgA Ab, which could not enter cells, served as a negative control for the neutralizing effects of MTS-conjugated dgA Ab.