FIG. 2.
Surface expression of vSAg7 and class II MHC proteins. Cell lines were analyzed by flow cytometry for vSAg7 (dashed lines) and/or class II IEk (dotted lines). Background fluorescence obtained using the control secondary reagent (phycoerythrin-streptavidin) is indicated (solid lines). vSAg7 and IEk expression was detected using biotinylated VS7 and fluorescein isothiocyanate-conjugated 14-4-4, respectively, as described previously (11). FD/S7 is a furin-deficient CHO cell variant (6) that was transfected with vSAg7. Mean channel fluorescence values of the cells within the markers on the histogram were as follows: CHO/S7 (clone 22.6) control, 4.01; VS7, 4.97; 14-4-4, 3.98; CH12.1 control, 7.11; 14-4-4, 589; CHIE (clone 13.2) control, 11.05; 14-4-4, 565; FD/S7 (clone 2.1) control, 4.68; VS7, 7.85; 14-4-4, 6.45. vSAg7 expression was not observed on CHIE or CH12.1 cells (data not shown). The partial loss of class II expression observed in the CHIE cells (c) was not characteristic of this cell line.