Upon PMA stimulation, the percentage of T lymphocytes expressing IL-4 was significantly higher in breast cancer patients than in controls (2.36 ± 0.49 vs 1.37 ± 0.16%, P=0.039), while the percentages of CD3+ cells expressing either IL-2 or IFN-γ were slightly decreased in cancer patients. Here, IL4 is linked to breast cancer.