Transient expansion of peptide-specific lymphocytes producing IFN-gamma after vaccination with dendritic cells pulsed with MAGE peptides in patients with mage-A1/A3-positive tumors.

Assessment of T-cell activation is pivotal for evaluation of cancer immunotherapy. We initiated a clinical trial in patients with MAGE-A1 and/or -A3 tumors using autologous DC pulsed with MAGE peptides aimed at analyzing T-cell-derived, IFN-gamma secretion by cytokine flow cytometry and ELISPOT. We also tested whether further KLH addition could influence this response favorably. Monocyte-derived DC were generated from leukapheresis products. They were pulsed with the relevant MAGE peptide(s) alone in group A (n=10 pts) and additionally with KLH in group B (n=16 pts). A specific but transient increase in the number of peripheral blood T lymphocytes secreting IFN-gamma in response to the vaccine peptide(s) was observed in 6/8 patients of group A and in 6/16 patients of group B. We conclude that anti-tumor vaccination using DC pulsed with MAGE peptides induces a potent but transient anti-MAGE, IFN-gamma secretion that is not influenced by the additional delivery of a nonspecific, T-cell help.