FIG. 1.

Immunoblot of human IgG in cytoplasmic extracts from PLC/PRF/5 cells (lanes 1 to 4) and HuH-7 cells (lanes 5 to 8). The cells were cultured with medium containing human AB serum (lanes 1 and 5), human AB serum plus 1.0 mg of monoclonal anti-HBs IgG/ml (lanes 2 and 6), medium with FCS alone (lanes 3 and 7), or 1.0 mg of monoclonal anti-HBs IgG/ml (lanes 4 and 8). As a standard, monoclonal anti-HBs IgG (mAb) was included in the blot. INT, intensity of the chemiluminescence signal measured by FluorS MultiImager in arbitrary units (au). Cellular IgG, estimated amount of IgG associated with cells; IgG uptake, relative amount of IgG associated with the cells as a percentage of the IgG in culture supernatants. The amount of the latter was calculated on the basis of the known IgG concentration (1.0 mg/ml) and the known volume of medium (2.5 ml) in each well, i.e., 2,500 μg of IgG.