Document Type : Research Articles
Department of Pathology, Dow International Medical College, Dow Diagnostic Research and Reference Laboratory, Dow University of Health Sciences Karachi, Pakistan.
Institute of Translational Immunology and Research Centre for Immunotherapy, Johannes Gutenberg University of Mainz, Germany.
Background: Patients with triple negative breast cancer (TNBC) have limited therapeutic options, largely because the complex tumour environment is not well-characterized. These patients are potential, but largely un-fathomed, candidates for immunotherapy. It is therefore highly relevant to characterize leukocyte complexity in TNBCs. Objective: To investigate leukocyte complexity in tumour environment of patients with TNBCs. Materials and methods: A total of 104 consecutive breast cancer patients undergoing mastectomy were recruited in the study after ethical approval. Clinico-pathological parameters were recorded and H and E staining was performed to investigate tumour morphology. Receptor status was investigated using antibodies against ER, PgR and Her-2, and patients were classified as having TNBC or non-TNBC tumours (including Luminal A, Luminal B and Her2 overexpressing tumours). Immune-cell infiltration was investigated using special stains and antibodies: α-CD3 (T-lymphocytes), α-CD20 (B-lymphocytes), α-CD4 (helper T-lymphocytes) and α-CD8 (cytotoxic T-lymphocytes). Immune cell densities were quantified as cell/ mm2 using the CAP guidelines. Results: Of the 104 breast cancer patients investigated, a total of 27 (26%) had TNBC and 77(74%) non-TNBC. Patients with TNBC showed significantly increased tumour infiltration of lymphocytes (T and B-lymphocytes) compared to the patients with non-TNBC, while myelocytic infiltration was not significantly different in the two groups. Within the TNBC group, infiltration of T-lymphocytes (equal densities of CD4+ and CD8+ T-lymphocytes) was significantly higher compared to B-lymphocytes. Conclusion: Patients with TNBC show increased lymphocytic infiltration (more T-lymphocytes compared to B-lymphocytes). This suggests higher immunogenicity of TNBCs and may indicate a higher responsiveness of these cancers to immunotherapy.