Dendritic cell vaccines generated from naïve or breast cancer-bearing mice are phenotypically similar

ABT, ARACELI A.; IMSEN, MERCEDES; ZANETTI, FLAVIA A.; NICOLA CANDIA, ALEJANDRO J.; ZUCCATO, CAMILA; BAL DE KIER JOFFÉ, ELISA; CANDOLFI, M; ASAD, ANTONELA S.; SAGRIPANTI, SOFIA; SEILICOVICH, ADRIANA

Mar del Plata

Congreso; LXIII Reunión de la Sociedad Argentina de Investigación Clínica; 2018

The use of dendritic cells (DCs) for antitumor immunotherapy has been widely studied in preclinical and clinical settings showing good safety profiles. Although these strategies exert robust antitumor effects in preclinical cancer models, clinical efficacy has been lower than anticipated. This discrepancy could rely in part in the fact that DC precursors are extracted from cancer patients to generate autologous vaccines, while in preclinical studies antitumor vaccines are commonly generated from DC precursors from healthy animals. Considering that there is discrepancy on the functionality of CDs collected from cancer patients, we aimed to characterize DCs cultured from the bone marrow of naïve and breast tumor-bearing mice. In order to optimize the culture conditions, we first evaluated the yield and purity of bone marrow cultures from naïve Balb/c mice grown for 7 days in medium supplemented with recombinant GM-CSF (rGM-CSF, 10 ng/ml) or 30% conditioned medium (CM) from GM-CSF-producing mouse B myeloma J558 cell cultures. The number of DCs obtained from these cultures was significantly higher when precursors were grown in J558 CM (2.1-3.0x106/mouse with 95% CD11c+ cells) than in rGM-CSF (0.6-1.8x106/mouse with 55% CD11c+ cells). We next characterized bone marrow cultures obtained from immunocompetent Balb/c naïve mice or mice bearing s.c. LM3 murine breast carcinomas. Cells were grown for 7 days in J558 CM, exhibiting similar yield between naïve (1.3-7.6 x106/mouse) vs tumor-bearing mouse bone marrow (0.6-5.0 x106/mouse). DCs from naïve or tumor bearing mice were then incubated with TLR9 agonist CpG1826 (10 µg/ml) and their activation status was assessed 48h later. Both cohorts of DCs exhibited comparable levels of IL-12 and IL-10 secretion, as assessed by ELISA, as well as MHCII and CD86 expression, as determined by flow cytometry. Our results suggest that DC precursors obtained from tumor-bearing mice retain the features of their normal counterparts.