T-cell infiltration into human cancer tissues can be a manifestation of host immune responses to cancer cells. The present study was undertaken to explore the clinicopathological significance of intraepithelial CD8 þ T cells using 371 consecutively sampled human colorectal carcinomas. By univariate analysis, we noted that the survival curves by intraepithelial CD8 þ T cells became separated only after 1 to 2 years postoperation. Multivariate analyses revealed that the beneficial effect of this factor becomes significant only after a longer (more than 2 year), but not after a shorter (less than 2 year) follow-up period. Furthermore, the number of intraepithelial CD8 þ T cells was significantly higher in patients alive for more than 5 years than in patients who either died of cancer after a curative operation or patients who underwent a noncurative operation. Patients' cancer-specific death long after a curative operation is thought to be caused by the growth of micrometastases in other organs or near the primary sites. The effects of intraepithelial CD8 þ T cells, therefore, may be mediated by suppression of micrometastasis, rather than suppression of growth in the primary tumour. In conclusion, our data support a hypothesis on the presence of systemic immunosurveillance against micrometastasis of cancer cells.

CD8+ T cells infiltrating within cancer cell nests in human colorectal cancer were associated with a favorable patients' survival, suggesting the presence of anti-tumor immunity. The present study was designed to examine this concept in non-small cell lung cancer (NSCLC) by a retrospective analysis of 128 surgically resected cases. Immunohistochemical analysis showed that the number of CD8+ T cells within cancer cell nests in NSCLC was related to the histological subtype (large cell carcinoma or squamous cell carcinoma > adenocarcinoma) and the degree of dedifferentiation (undifferentiated type > differentiated type). In contrast to colorectal cancer, the number of CD8+ T cells in NSCLC had no statistically significant impact on the patients' survival. The present study demonstrated that the degree of infiltration of CD8+ T cells within cancer cell nests is dependent on the dedifferentiation of cancer cells in NSCLC, which could be one of the important aspects for the study of tumor immunity.

cnm-positive S. mutans strains are potentially associated with the pathogenesis of IgAN.

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