Activated monocytes prime naïve T cells against autologous cancer: vigorous cancer destruction in vitro and in vivo.

It has not been considered so far that antigen-presenting cells (APC) may phagocytose immunogenic material from autologous cancer cells. Assuming the presence of cancer-immunogenic material in APC, we developed a novel autologous priming method that does not require tumour cells or identified peptides. Cancer-immunogenic information came from CD14+ monocytes. When stimulated with CD3-activated T cells, monocytes primed CD3+ CD4+ and CD3+ CD8+ resting/naïve T cells to become powerful effector cells within 24 h. During priming, depletion of CD14+ monocytes but not CD1a+ CD83+ dendritic cells prevented T cell priming. During cancer cell destruction, dendritic cells, but not monocytes, enhanced cancer cell lysis. The cascade-primed (CAPRI) immune cell quartet comprising monocytes, dendritic cells, CD4+ T and CD8+ T cells induced a significant decrease in the number of suppressive CD25(high) FoxP3+ CD4+ T cells. CAPRI cells induced a marked upregulation of MHC class I and class II expression in cancer cells, which is crucial for autoimmune-like lysis. We show in vivo evidence of the CAPRI cell concept in nude mice. In humans, we present circumstantial clinical evidence showing the efficacy of CAPRI cells in an adjuvant treatment attempt for breast cancer patients with metastasis (N = 42). Compared to patients at the Munich Tumor Center (no CAPRI treatment N = 428), almost double the expected number of patients survived 5 years (P =1.36 × 10⁻¹⁴). The CAPRI method is a safe procedure without negative side effects. High numbers of cancer-specific CAPRI cells can be obtained within a week against different cancer types for efficient adoptive cell therapy.