Functional tumor reactive T cells in bone marrow and blood of pancreatic cancer patients.

4113 Background: Memory T-cells specifically reactive to tumor antigens should be an ideal source to generate therapeutic effector cells against pancreatic cancer. To our knowledge functionally active, specific memory T-cells have not been demonstrated in pancreatic cancer patients. To investigate if functional memory T-cells are present in the bone marrow (BM) of pancreatic cancer patients, we performed in vitro stimulation with tumor associated antigens presented by autologous dendritic cells (DC).,DC and T-cells were generated in a 14-day culture with GM-CSF and IL-4 (DC) and/or IL-2, IL-4, IL-7 (TC) from BM derived CD34+ progenitor cells of 35 patients with pancreatic carcinoma and chronic pancreatitis. DC were pulsed with lysate from autologous tumor cells, Muc I peptide - fragments and PBMCs (peripheral blood mononuclear cells as negative controls). Tumor specific T-cell response was evaluated in a single-cell interferon-γ-, IL4-, IL10- and IL12- release immunospot assay (Elispot). Cytotoxicity of CD8+ T-cells against primary cultured tumor cells was measured by a functional DNA-release, and trypan-blue staining assay.,In the individual patient, T-cells stimulated by tumor lysate pulsed DC as well as DC pulsed with Muc I peptide showed a significantly higher response in the INF-γ Elispot assay compared with T-cells stimulated by PBMC-lysate pulsed DC. The tumor specific T-cell frequency found in the bone marrow was consistently high (49/10 to 109/10) in all patients compared with the response found in the periferal blood (9/10 to 53/10; p<0,05 to p<0,001). In the cytotoxicity assay, the response was significantly higher when T-cells were stimulated with tumor lysate pulsed DC compared with PBMC-lysate pulsed DC.,Our data indicate for the first time a regular occurrence of tumor antigen specific T cell responses during the course of pancreatic cancer that lead to the generation and enrichment of functional tumor cell-reactive memory T cells in the bone marrow. The BM may therefore be considered an important lymphoid organ for the induction or maintenance of anti tumor immune responses in pancreatic cancer. No significant financial relationships to disclose.