Immunohistochemical Evaluation of CD3+ and CD8+ tumour-Infiltrating Lymphocytes and their Association with Clinicopathological Features in Breast Cancer

• Shahad Alqaraagholi

  Microbiology Department, College of Medicine, University of Thi-Qar, Thi-Qar, 64001, Iraq

• Dhafer A. Alghezi

  Microbiology Department, College of Medicine, University of Thi-Qar, Thi-Qar, 64001, Iraq and Basic Science Department, College of Dentistry, University of Thi-Qar, Thi-Qar, 64001, Iraq

• Rasha Q. Aljawher

  Histopathology and Forensic Medicine Department, College of Medicine, University of Thi-Qar, Thi-Qar, 64001, Iraq

Background: Breast cancer represents one of the most prevalent malignancies, with progression influenced by both tumour biology and the immune microenvironment. However, current prognostic methods have limited accuracy in predicting tumour aggressiveness and long-term outcomes. Tumour-infiltrating lymphocytes, principally CD3⁺ and CD8⁺ T cells, may play an important role in antitumour immunity.

Objective: The primary goal of the study is to assess the immunostaining of CD3 and CD8 proteins in malignant and non- malignant breast tissue and to find their association with breast cancer histopathological data using immunohistochemistry.

Methodology: This research was conducted between December 2025 and March 2026 at Al-Nasiriyah Teaching Hospital in Thi-Qar, Iraq. Immunohistochemical analysis was performed to evaluate CD3⁺ and CD8⁺ T-cell expression in both malignant (n=100) and non-malignant (n= 40) tissues of the breast. Statistical analyses were applied using unpaired t-tests, Chi-square and one-way ANOVA to assess differences in immunostaining levels between the studied groups.

Result: The findings demonstrated that CD3⁺ and CD8⁺ immunostaining levels were significantly elevated in both stromal and intra-tumoural regions of malignant breast tissues compared to benign tissues. The immunostaining of these potential biomarkers was associated with higher tumour grade, larger tumour size, lymph node metastasis, and the molecular subtypes of breast cancer.

Conclusion: Increased CD3 and CD8 expression in breast cancer is strongly linked to more advanced histopathological parameters. The findings indicate that these immune biomarkers may reflect the tumour immune microenvironment and contribute to a more comprehensive understanding of tumour progression and host immune response in breast cancer.

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