Figure 5.

Cell protein synthesis inhibition assay. D430B and Raji cells were treated with HMW-IT (square), LMW-IT (triangle), free saporin-S6 (white circle) or a mixture of unconjugated Rituximab and saporin-S6 (black circle). The cells (5 × 10³) were seeded in 96-well plates in a total volume of 200 μL of complete medium (see Matherials and Methods) containing various concentrations of substances. After 96 h of incubation and a further 6 h with [³H]-leucine, the incorporated radioactivity was determined. The results are the means of two independent experiments, each performed in triplicate. SD was <10%. Data were analyzed by the ANCOVA/Bonferroni test. The inhibition of protein synthesis by HMW-IT differed significantly (p < 0.001) from that by LMW-IT. Both immunotoxins significantly inhibited protein synthesis with respect to the free RIP and mixture (p < 0.0001).