Immunesurveillance by dendritic cells: potential implication for immunotherapy of endocrine cancers

Dendritic cells (DCs) are highly efficient antigen-presenting cells in the immune system with the potential to regulate the system and induce a cytotoxic T-cell response. As a proof of principle, a multitude of animal and human studies has demonstrated that immunization with antigen-loaded DCs may lead to anti-tumour immune responses with tumour regression and rejection of cancer. The identification of tumour antigens that can be recognized by T lymphocytes has facilitated the development of new protocols and enabled immunologists to monitor immune responses. However, to date, long-term clinical effects on larger numbers of cancer patients are missing, and there is no generally accepted DC generation or activation protocol. This review will focus on the most important findings on the role of DCs within the immune system and how to generate and activate these cells in order to induce cytotoxic immunity in non-endocrine and endocrine malignancies. Recently, we and other researchers reported on DC vaccinations in patients with endocrine malignancies mainly in metastasized medullary thyroid carcinoma resulting in tumour-specific immunity and partial clinical responses in some cases. Based on these and other in vitro data, new DC vaccination protocols for the treatment of patients with endocrine tumours have now been conducted.