Background: We recently demonstrated that supernatants from cultures of peripheral blood mononuclear cells (PBMC) activated with anti-CD3-specific antibody (ACD3S) can induce, upon brief exposure, tumor-reactive lymphocytes in cancer patients. Here, we report that ACD3S can also induce rapid and stable maturation of dendritic cells (DC) which can be used as antigen presenting cells in in vitro protocols and for cancer immunotherapy in vivo.
Materials and methods: A short (4-day) priming of CD14+ monocytes with granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-4 (IL-4) followed by only a 24 hour-incubation in ACD3S, is sufficient to generate fully mature and stable DC.
Results: These DC (i) stimulated strong T cell proliferative responses in the mixed lymphocyte reaction, (ii) when pulsed with unfractionated peptides from autologous tumor membrane extracts activated CD4+ T cells which proliferated in response to the autologous tumor and CD8+ cytotoxic T cells (CTL) which specifically lyse autologous tumor targets and (iii) produced high levels of IL-12.
Conclusion: ACD3S-treated DC are functionally superior to monocyte-conditioned medium (MCM)-treated DC generated under the same short-term protocol and as efficient as DC induced by the standard 10-day protocol. Our data present an efficient and effective method for generating in a very short period of time, highly mature and functionally competent DC.