ALTERED LYMPHOCYTE POPULATIONS IN TUMOR INVADED NODES OF BREAST-CANCER PATIENTS

Lymphocytes from matched pairs of tumour-invaded and tumour-free lymph nodes from 22 stage II breast cancer patients have been analysed for expression of phenotypic and activation markers by flow cytometry. Although the relative proportions of T and B lymphocytes were similar in the two nodes, significant differences in the distribution of T cell subsets were observed between nodes that were invaded and those that were not. The CD4/CD8 ratio was markedly depressed in tumour invaded nodes (P<0.001). This was due to an increase in the number of CD8+ T cells (P < 0.001) and a decrease in the CD4+ T cell population (P=0.008) in invaded nodes in comparison with tumour-free nodes. The percentage of CD8+ T cells expressing HLA DR (P=0.023) and IL-2 receptors (Tac) (P=0.029) was significantly higher in invaded nodes and, while CD4+ T cells expressing HLA DR (P=0.036) were also in a higher proportion in invaded nodes, the difference in the proportion of Tac expressing CD4+ T cells failed to reach significance. Although invaded nodes in a few patients were found to have a higher percentage of IgG-expressing B cells, no significant differences were observed between the two groups of nodes. These results suggest that the presence of metastatic tumour cells in a lymph node is associated with specific alterations in the T cell population.