In Vitro and in Vivo Cytotoxicity to EL-4 Sarcoma in New Zealand Mice

Abstract

The immune response to EL-4 tumor was studied in female NZB/W, BALB/c and CDF₁ mice after both in vivo and in vitro immunization with spleen cells as attackers and ⁵¹Cr-labeled EL-4 cells as targets. NZB/W mice demonstrated marked changes with age in the cytotoxic response after both in vivo and in vitro sensitization, whereas the other strains did not. These changes were characterized by hyporesponsiveness at 9 months of age, and hyper-responsiveness at 6 months of age, relative to 1 month of age. Antibody to EL-4 tumor was found in unimmunized NZB/W mice and tended to increase with age. Nevertheless, the cytotoxic antibody response in NZB/W mice after in vivo sensitization was similar at 1 month and 6 months of age, but was reduced at 9 months of age. Nine-month-old NZB/W mice failed to mount an adequate cytotoxic response and were killed by the tumor, whereas 1- and 6-month-old animals mounted cytotoxic responses and survived.