Figure 6.

IHC analysis of antibody fragment penetration. Top, spheroids were incubated in suspension with three different concentrations of green fluorescent sm3E scFv for 48 h. The spheroids were then processed for IHC and labeled with a noncompeting anti-CEA antibody (blue fluorescence). The two highest concentrations have a φ² of <6 and are predicted to be saturated. Bottom, Pearson correlation coefficients were calculated for the fluorescence intensity of sm3E and antigen. Pixels with no fluorescence in either channel (background) were excluded from the analysis. Scatter plots of the fluorescent pixels are shown for all three images. Scale bar, 100 μm.