Identification of a new subset of cells exhibiting dendritic phenotypes in patients affected by breast proliferative disorders

We report that a subset of circulating cells reacting with a monoclonal antibody raised against a protein marker is significantly increased in the peripheral blood of women carrying benign or malignant breast diseases, particularly in patients under 55 years of age with ductal mammary carcinomas. These cells were statistically (confidence level of 99%) less represent ed in a control population including healthy women or women carrying carcinomas of origin other than breast. Double staining analysis showed that they harbor markers of dendritic cells and exhibit endocytic activity, as determined by their ability ro internalize FITC-dextran particles. Their dendritic morphology was further demonstrated by electron microscopy of sorted antibody-positive cells. However, expression of surface molecules, such as CD34 and CD14, usually not present in differentiated populations of dendritic cells was also observed. Adherent cells of patients with breast ductal carcinoma including mostly cells of this new subset were efficient stimulators of mixed lymphocyte reaction, attaining maximal stimulatory activity attained after TNF alpha treatment. In conclusion, we have shown that a subset of cells characterized by a phenotype suggestive of a yet undescribed stage of maturation of the dendritic cell lineage is accumulated in the blood of patients affected by breast proliferative disorders. Human Immunology 61, 739-752 (2000). (C) American Society for Histocompatibility and Immunogenetics, 2000; Published by Elsevier Science Inc.