Elevated level of peripheral CD8+CD28- T lymphocytes are an independent predictor of progression-free survival in patients with metastatic breast cancer during the course of chemotherapy

Suppression of cellular immunity resulting from tumorigenesis and/or therapy might promote cancer cells' growth, progression and invasion. Here, we explored whether T lymphocyte subtypes from peripheral blood of metastatic breast cancer (MBC) female patients could be used as alternative surrogate markers for cancer progress. Additionally, plasma levels of interleukin (IL)-2, IL-4, IL-6, IL-10, IFN-gamma, and transforming growth factor-beta 1 were quantitated from MBC and healthy volunteers. This study included 89 female MBC patients during the post-salvage chemotherapy follow-up and 50 age- and sex-matched healthy volunteers as control. The percentages of T lymphocyte subpopulations from peripheral blood and plasma levels of cytokines were measured. Both CD8(+)CD28(-) and CD4(+)CD25(+) were elevated in MBC patients compared to the control cohort (P < 0.05). In contrast, CD3(+) and CD8(+)CD28(+)cells were significantly lower in MBC patients (P < 0.0001, P = 0.045, respectively). MBC patients had elevated levels of immunosuppressive cytokines IL-6 and IL-10. Patients with elevated CD8(+)CD28(-) and CD4(+)CD25(+) cells showed increased levels of IL-6, and only patients with elevated CD8(+)CD28(-) had decreased interferon-gamma. Univariate analysis indicated increased CD3(+)CD4(+) or CD8(+)CD28(+)correlated with prolonged progression-free survival (PFS), while elevated CD8(+)CD28(-)associated with shorten PFS. The percent of CD8(+)CD28(-) T lymphocytes is an independent predictor for PFS through multivariate analysis. This study suggests that progressive elevated levels of CD8(+)CD28(-) suppressor T lymphocytes represent a novel independent predictor of PFS during post-chemotherapy follow-up.