SUPER-SENSITIVE EPITHELIAL-CELL LINE AND COLORIMETRIC ASSAY TO REPLACE THE CONVENTIONAL K562 TARGET AND CHROMIUM RELEASE ASSAY FOR ASSESSMENT OF NON-MHC-RESTRICTED CYTOTOXICITY

Using colorimetric MTT assay the susceptibility of a newly established bladder epithelial cell line, Fen cells was compared with conventiona l target cells, i.e., K562 and Daudi and other epithelial lines for in vestigation of non-specific killing activity (NK/LAK) of effector cell s previously activated with interleukin-2 (IL-2). The results showed t hat Fen cell line was more sensitive than K562 and Daudi targets and t his was seen whether the effector cells were IL-2-activated or not. Th e percent killing of effector cells from nine normal donors against Fe n, K562 and Daudi targets at effector/target (E/T) ratio of 10/1 after IL,-2 activation were 63.4 +/- 7.3, 42.6 +/- 4.3 (p = 0.0001) and 38. 6 +/- 5.1 (p = 0.0001) respectively. The corresponding values for inac tivated effector cells at 50/1, E/T ratio were 44.8 +/- 9.0, 25.1 +/- 8.3 (p = 0.0001) and 24.4 +/- 9.4 (p = 0.0001) indicating exquisite se nsitivity of Fen cells to NK/LAK killing. The susceptibility of Fen ce lls was found to increase by pre-treatment of target cells with interf erons (IFN). Thus the percent killing of untreated, IFN-alpha (1000 U/ ml), beta (2000 U/ml) and gamma (100 U/ml) treated cells were 52%, 64% (p = 0.005), 70% (p = 0.001) and 67% (p = 0.001) respectively. These results indicated that Fen cells were more susceptible to NK/LAK killi ng than the conventional K562 and Daudi target cells. These results an d the epithelial origin of Fen cells indicate that this cell line migh t prove to be a more realistic system to replace the conventional appr oach for assessment of NK/LAK activity in patients with cancer of epit helial origin.