Background: Analysis of serum cytokine levels has shown that cancer-bearing hosts have lower levels of IL-2 and IFN-gamma, suggesting that Th1-type immunity is impaired by cancer. However, the mechanisms of the Th1 dysfunction are not clearly understood.
Method: The frequencies of Th1 cells in CD4(+) helper T cells were evaluated with an intracytoplasmic cytokine staining method in peripheral blood lymphocytes (PBL) and lymph node lymphocytes (LNL) of patients with gastrointestinal cancer.
Results: Activation of lymphocytes with PMA + Ionomycin induced the expression of IL-2 and IFN-gamma in each lymphocyte population. Compared with PBL of non-malignant donors, PBL in cancer patients contained significantly lower frequencies of CD4(+) T cells that produced IL-2 and IFN-gamma. LNL in cancer patients also contained lower levels of IL-2- and IFN-gamma-producing CD4(+) T cells, although the percentages did not show significant differences from those of PBL in the same patients.
Conclusion: Our data suggest that suppression of Th1 cytokine in cancer patients is, at least in part, due to the decreased frequency of Th1 cells with CD4(+) phenotype.