Low CD4 Counts Signal Tumor Metastases.
In a study of 30 women with stages Ia to IIa cervical cancer, low CD4 counts and reversal of the normal ratio of CD4 to CD8 cells were associated with rapid tumor growth and the appearance of lymph node metastases, said Dr. Huang of National Taiwan University Hospital, Taipei.
Using flow cytometry to quantify T-cell populations and subpopulations infiltrating the cervix, Dr. Huang reported finding a strongly reversed CD4 to CD8 ratio in bulky tumors. The proportion of CD4 cells normally exceeds that of CD8 cells.
But in bulky cervical tumors in this study, only 21.4% of the lymphocytes were CD4 cells, as were 32.5% in nonbulky tumors. And at only 24.5% of the total lymphocyte count, the proportion of CD4 cells also was significantly lower in patients with lymph node metastases than in those with no metastases, where CD4 count averaged 32.7% of the total.
"This novel finding sheds new light on the understanding of tumor-mediated immunosuppression," Dr. Huang said at the meeting, which was also sponsored by the American College of Obstetricians and Gynecologists.
"Low CD4 counts also have been reported in melanoma and bladder cancer," Dr. Huang added, suggesting that this may be a universal prognostic indicator in cancer resulting from an inadequate antitumor response by the immune system.
Some researchers have hypothesized that immune system failure to eradicate tumor cells may relate to the presence of tumor-associated macrophages that mediate the release of cytokines while producing tumor-promoting factors (J. R. Coll. Surg. Edinb. 45:1-16, 2000). Other investigators have suggested that tumor progression may occur because of poor recognition of tumor antigens by the immune system or through the induction of anergy in lymphocytes (Pharmacol. Ther. 81:111-19, 1999). Suppression of immune responses and lymphocyte activity by tumor-derived factors also may contribute.