title: In breast cancer, a high ratio of tumour-infiltrating intraepithelial CD8+ to FoxP3+ cells is characteristic for the medullary subtype.
abstract: OBJECTIVE
  Medullary breast cancer (MBC) is a biologically distinct subtype of breast cancer characterized by prominent lymphocytic infiltrates and a favourable clinical outcome. Tumour-infiltrating CD8+ effector T cells may contribute to the good prognosis of this type of cancer; however, certain subtypes of lymphocyte, such as FoxP3+ regulatory T cells (Tregs), can also suppress antitumour immunity.
  
  
  RESULTS
  We determined tumour infiltration by FoxP3+, CCL22+ and CD8+ cells in paraffin-embedded sections of MBC, and, as a reference, in samples of grade 3 ductal, lobular and mucinous breast cancer. All analysed MBCs were strongly infiltrated by FoxP3+ cells, whereas only weak infiltrates were detected in ductal or lobular breast cancer. This finding was unexpected, given the good prognosis of MBC. Strikingly, the number of CD8+ T cells exceeded the number of FoxP3+ cells in MBC (ratio of CD8+ to FoxP3+ cells of 2.6), whereas equal amounts of both cell types were found in ductal breast cancer (ratio of CD8+ to FoxP3+ cells of 1.1). In both types of breast cancer, we also detected cells expressing the Treg-attracting chemokine CCL22.
  
  
  CONCLUSIONS
  In breast cancer, a predominance of tumour-infiltrating CD8+ over FoxP3+ cells was observed in MBC. Thus, the ratio of CD8+ to FoxP3+ cells rather than the absolute number of intratumoral FoxP3+ cells may be predictive for the clinical outcome of cancer.
authors.affiliation: Centre of Integrated Protein Science Munich, Division of Clinical Pharmacology, Ludwig Maximilian University, Munich, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Anz
authors.forename: Stephan
authors.initials: S
authors.lastname: Eiber
authors.forename: Christoph
authors.initials: C
authors.lastname: Scholz
authors.forename: Stefan
authors.initials: S
authors.lastname: Endres
authors.forename: Thomas
authors.initials: T
authors.lastname: Kirchner
authors.forename: Carole
authors.initials: C
authors.lastname: Bourquin
authors.forename: Doris
authors.initials: D
authors.lastname: Mayr
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000276:immunology / Q000473:pathology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D018276:Carcinoma, Medullary / Q000276:immunology / Q000473:pathology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D051858:Forkhead Transcription Factors / Q000276:immunology*; D006801:Humans; D007150:Immunohistochemistry; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology*; D008875:Middle Aged; D009367:Neoplasm Staging; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors