SPN and leukemia: Even at low E/T ratio (0.3), substantial percentages of CD43-deficient leukemia cells (25.8 ± 4.1% (clone E4) and 24.5 ± 2.3% (clone H8)), but not the wild-type leukemia cells (0.0 ± 0.0% (clones F3 and H9)), were lysed by OVA-specific CTLs (p<0.05) (Fig 5E), indicating that CD43 protects leukemia cells from attack by CTLs.