Guo X et al. - In a study to explore possible mechanisms underlying the finding that tumor infiltrating lymphocytes were associated with increased lymph node metastasis and a poorer prognosis, it was found that effective immunity provided by tumor infiltrating lymphocytes varies in different tumors and the relative lack of tumor-killing cytotoxic T lymphocytes in invasive micropapillary carcinoma may explain, in part, the adverse association of tumor infiltrating lymphocytes with biological behavior of invasive micropapillary carcinoma of breast Methods
28 cases of invasive micropapillary carcinoma with prominent lymphocyte infiltration were compared with 29 cases of medullary carcinoma
Results
In both tumors, the majority of tumor infiltrating lymphocytes were T lymphocytes with CD8+ T lymphocytes predominant
Functional differences in CD8+ cytotoxic T lymphocytes were identified in the 2 types of tumor
While lymphocytes infiltrated both the stroma and epithelial components of medullary carcinoma, the tumor infiltrating lymphocytes of invasive micropapillary carcinoma were almost exclusively confined to the stroma
Tumor infiltrating lymphocytes of medullary carcinoma showed stronger expression of FasL than those in invasive micropapillary carcinoma and medullary carcinoma cells exhibited stronger expression of Fas than invasive micropapillary carcinoma cells did
In the subgroups of tumors with strong (++/+++) Fas expression, double immunohistochemistry revealed that most of the tumor infiltrating lymphocytes in medullary carcinoma, particularly those infiltrating the tumor nests, were CD8+ cytotoxic T lymphocytes, but not so in invasive micropapillary carcinoma
Upregulated expression of perforin, granzyme B, and FasL by cytotoxic T lymphocytes was greater in medullary carcinoma than invasive micropapillary carcinoma
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