Characterization of T-lymphocyte subpopulations infiltrating primary breast cancer

Abstract

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 (greater than 40 lymphocytes per x 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 less than 0.0005). The most significant drop was in the stroma area (P less than 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.