Abstract
Freshly explanted MDAY murine tumor cells are sensitive to lysis mediated by fresh normal rabbit serum. The sensitivity, which increases with the age of the tumor, is rapidly lost upon short-term culture, and takes place at 37 °C but not at 4 °C. Cellular components released into the medium during short-term culture are capable of eliciting xenogeneic antibodies that mediate complement-dependent lysis of such cells.