Reproducibility of the tumor IFN-γ ELISPOT assay. Pre- and postvaccine PBMC from three patients (P 1–3) were co-cultured with autologous sCD40Lt activated tumor cells for 48 h as described in Materials and Methods. All samples were tested blinded in three independent experiments by three technicians. The numbers of spots per 1 × 105 effectors were significantly (p ≤ 0.001) higher in the postvaccine as compared to the prevaccine samples for all three patients. For each patient the data is presented as spots per 1 × 105 effector cells. The correlation of the results between technicians was highly significant (R2 above 0.9 for all experiments).