Analysis of human classical and non-classical monocytes compared to their dendritic cell counterpart.

Peripheral blood monocytes are the starting material utilized in conventional dendritic cell (DC) vaccination for the treatment of a broad range of malignancies. While the use of cytokines and growth factors to polarize monocyte-derived DC to distinct phenotypes is well-established, little is known about the contributions of distinct human monocyte subsets to monocyte-derived DC function and patient responses to vaccination. To investigate the status of monocyte subsets in cancer patients and following culture into DC, we isolated classical (C-Mo), intermediate (I-Mo), and non-classical (NC-Mo) from the peripheral blood of renal cell carcinoma (RCC) patients prior to DC vaccination (NCT00085436) and from anonymous healthy donors. Patients treated with DC vaccination who were long term survivors (>100 months survival) had a unique monocyte signature with a two-fold higher percentage of NC-Mo in pretreatment peripheral blood compared to other RCC patients. RCC patient monocytes from each subset were transcriptionally distinct from healthy donor monocytes. Further transcriptional analysis determined that each monocyte subset was characterized by a discrete gene expression profile before and after DC maturation. Phenotypic analysis showed that DC derived from NC-Mo expressed higher levels of CD80, CD83, CD86, HLA-DR, and CD40 compared to DC originating from C-Mo and secreted increased amounts of IL-12p70 following CD40L stimulation. Collectively, these findings establish that DC derived from NC-Mo are potent antigen presenting cells and provide the foundation for future vaccination strategies that enrich NC-Mo prior to DC maturation. Classical and non-classical monocytes were FACS purified from peripheral blood obtained from 3 healthy donors and either used for transcriptional analysis or cultured into dendritic cells for analysis.