Table I.

Phenotypic comparison of SW480 to SW620 colon carcinoma cells before and after IFN-γ pretreatmenta

Tumor Cell LineIFN-γ PretreatmentmAb Directed Against % Positive Cells (MFI)
HLA-A2ICAM-1LFA-3Fas
SW480Untreated72 ± 839 ± 696 ± 0.413 ± 4
(68 ± 7)(42 ± 6)(114 ± 9)(30 ± 2)
Pretreated 97 ± 1 98 ± 1 96 ± 0.4 65 ± 4
(544 ± 32) (289 ± 35) (90 ± 9)(41 ± 3)
SW620Untreated96 ± 153 ± 897 ± 0.42 ± 0.4
(100 ± 10)(35 ± 5)(92 ± 5)(18 ± 2)
Pretreated97 ± 0.4 95 ± 1 96 ± 1 15 ± 4
(499 ± 23) (214 ± 26) (70 ± 3)(20 ± 1)
  • a Tumor cells, either untreated or pretreated with IFN-γ, were evaluated by flow cytometry for cell-surface expression of the indicated molecule. Data were expressed as the mean ± SEM of the percentage positive cells and MFI (in parentheses) of 8 (for HLA-A2, ICAM-1), 4 (for LFA-3), and 12 (for Fas) separate experiments. Staining with the appropriate isotype control Ab, which ranged from 2 to 10%, was subtracted from the values shown above. Data in bold type indicate statistically significant responses, based on comparison with the corresponding untreated preparations. For SW480 cells: HLA-A2: percentage positive cells, p < 0.02; MFI, p < 0.0001; ICAM-1: percentage positive cells, p < 0.0001; MFI, p < 0.0001; Fas: percentage positive cells, p < 0.0001. For SW620 cells: HLA-A2: MFI, p < 0.0001; ICAM-1: percentage positive cells, p < 0.001; MFI, p < 0.001; Fas: percentage positive cells, p < 0.005.