Characterization of T-lymphocyte subpopulations infiltrating primary breast cancer

Characterization of T-lymphocyte subpopulations adjacent to and infiltrating the primary tumor of breast cancer was carried out using a direct immunofluorescence procedure with the antibodies anti-(Leu-2a) for suppressor/cytotoxic (CD8⁺) and anti-(Leu-3a) for helper/inducer (CD4⁺) T-lymphocytes. Fifty-six primary malignant tumors with lymphoid infiltration were studied. The majority (58.9%) were infiltrating duct carcinoma. There were metastases to axillary lymph nodes in 6.67% of the patients. Massive lymphoid infiltration (>40 lymphocytes per ×400 microscopic field) was found in 19.6% of the tumors and moderate infiltration (20-40 lymphocytes per field) in 51.8%. In all the tumors studied there was a reversed CD4⁺/CD8⁺ ratio as compared to that found in normal peripheral blood. In 66.1% the CD4⁺/CD8⁺ ratio (helper/suppressor) was less than 1.0. The reversed ratio was due to a significant decrease in the number of helper cells (P<0.0005). The most significant drop was in the stroma area (P<0.0001) as well as in the tumor tissue (P=0.001). Of particular interest was the significant positive correlation between the age of the patients and an increased number of CD4⁺lymphocytes in the stroma (P=0.02). Significant negative correlations were found between a reduced number of CD4⁺ lymphocytes or CD4⁺/CD8⁺ ratio and several histological parameters: tumor diameter, pleomorphism, nucleus/cytoplasm ratio. There was also a significant positive correlation between the total number of CD8⁺ lymphocytes infiltrating the tumor tissue and the number of axillary lymph nodes with metastatic disease (P=0.03). It is suggested that the reversed ratio of CD4⁺/CD8⁺ lymphocytes may significantly affect the host/tumor immune surveillance.