Effect of red blood cells on the antitumor activity of oxycellulose

The antitumor activity of oxycellulose to MH134 tumor cells, evaluated with microscopic viable cell count, was suppressed by murine red blood cells (MRBCs) in a dose-dependent manner. The antitumor activity of oxycellulose was suppressed by MRBCs also when evaluated with 3H-TdR uptake. However, that of mitomycin C or 5-fluorouracil was not suppressed by MRBCs. On the other hand, the antitumor activity of oxycellulose was suppressed by MRBCs also when evaluated with 51Cr release assay. At that time, the antitumor activity of cisplatin to MH134 tumor cells were not suppressed by MRBCs. The antitumor activity of oxycellulose to MH134 tumor cells was suppressed by the membrane or the cytosol fraction of the lysate of MRBCs as well as intact MRBCs. When heated at 56 degrees C for 30 min, MRBCs were unable to suppress the activity of oxycellulose. It was examined whether or not proteins related to MRBCs (hemoglobin, catalase, superoxide dismutase or taurine) suppressed the activity of oxycellulose. They did not suppress the activity of oxycellulose.