CTL activity of the splenic cells of immunized mice and rats. Three groups of animals, either Swiss mice (A) or Sprague Dawley rats (B), were immunized i.v. with PBS, BTAA alone or BTAA in combination with NLP weekly for 4 weeks. Seven days after the last injection, splenic cells from individual mice were isolated, cultured in the presence of BTAA for 3-5 days and a CTL assay performed using these cells as effectors and MCF-7 cells as target at an E:T ratio 10:1. Each data represents the mean value ± 1 SD. *Significantly higher as compared to other values (P < 0.001).