Phenotypic characterisation of the dendritic cell infiltrate in prostate cancer

Purpose: To investigate whether dendritic cells (DC), which as professional antigen presenting cells have the capacity to stimulate immune responses against tumour associated antigens, are recruited into and activated within prostate cancer. Materials and Methods: Immunoenzyme and immunofluorescence labelling was used to identify leucocyte and DC subsets within 15 cases of prostate cancer. Cell numbers were compared with numbers in adjacent normal prostatic tissue. Total DC numbers were identified as CD45(+) leucocytes not coexpressing any lineage specific markers. The Langerhans cell (LC) subset was detected using anti CD la staining and activated DC were identified by their expression of either CD83, CD86 or CMRF44. Results: DC were found to represent a small subset of leucocytes present in both benign and malignant prostatic tissue. Statistically there were significantly less DC and LC in prostate cancer compared with normal prostatic tissue, While only a small subset of DC expressed markers of activation in prostate cancer, this was significantly more than the virtual absence of activated DC in normal prostatic tissue. Conclusions: This is the first time that DC have been studied in prostate cancer using the relatively new DC specific monoclonal antibodies CD83 and CMRF-44. These findings suggest that there is no active recruitment of DC into prostate cancer and those DC present are only minimally activated.