Splenocytes from hspE7-immunized mice are cytotoxic for TC-1 cells in vitro. C57Bl/6 mice (three per group) were injected subcutaneously with either PBS, 1·4 nmol (h)E7 or 1·4 nmol hspE7. Animals were boosted 7 days later. Seven days after the boost, pooled splenocyte cultures were prepared and re-stimulated for 5 days with mitomycin C-treated TC-1 cells and tested for cytolytic activity against the following 51Cr-labelled target cells: MC38 (irrelevant target; □) or the E7-expressing tumour cell line TC-1 (▪). Data are expressed as mean ± s.e.m. of percent corrected lysis from three independent experiments, using ct/min of released radioactivity detected in supernatants of cultures after 4 h of effector:target incubation at the indicated ratios. **(h)E7 versus hspE7 for TC-1, P < 0·05 and PBS versus hspE7 for TC-1, P < 0·02; *PBS versus hspE7 for TC-1, P < 0·05.