Figure 4.

Sensitivity of primary breast tumor to CPE-mediated cytolysis in vitro. A: Freshly resected primary breast tumor tissue samples of approximately 5 to 10 mm³ were divided into two equal pieces and incubated with or without 10 μg CPE in DMEM supplemented with 10% fetal bovine serum for a period of 12 hours. Tissues were subsequently fixed in 10% neutral buffered formalin, paraffin embedded, sectioned, and stained with H&E. Sections were visualized by light microscopy (×200). B: Primary breast carcinoma cells were isolated from freshly resected breast tumor using the epithelia-specific antibody BerEP4 conjugated to magnetic beads as described in Materials and Methods. Cells were aliquoted equally into the wells of a 6-well plate and treated with or without CPE at a final concentration of 2 μg/ml for 60 minutes. Percent cytotoxicity was determined by comparison of non-ballooned cell counts within a demarcated 1-cm² grid at 0 and 60 minutes following the addition of CPE. The breast cancer cell lines MCF-7 and HS578T were included as positive and negative controls, respectively.