Effects of distant metastasis and peripheral CA 15-3 on the induction of spontaneous T cell responses in breast cancer patients

Abstract

Tumor-specific memory T cells are detectable in the bone marrow (BM) of a majority of breast cancer patients. In vitro they can be reactivated to IFN-gamma producing, cytotoxic effector cells and reject autologous, xenotransplanted tumors in NOD/SCID mice after specific restimulation with autologous dendritic cells (DC). In this study, we demonstrate the presence of specific tumor-reactive BM memory T cells in altogether 56 out of 129 primarily operated breast cancer patients by short-term IFN-gamma EliSpot assays with unstimulated T cells and tumor antigen presenting, autologous DCs. We observed tumor-reactive BM memory T cells predominantly in patients with primarily metastatic disease (P = 0.011) or with increased concentrations of tumor marker CA 15-3 in the peripheral blood (P = 0.004), respectively. Memory T cell reactivity against HLA-A(*0201)-restricted peptides from the tumor-associated antigens MUC1, Hpa(16-24) and Hpa(183-191) was also detected particularly in patients with elevated peripheral CA 15-3 concentrations (P < 0.05). Altogether these data indicate that the systemic presence of tumor-derived antigens promotes an induction of tumor-specific cellular immune responses in the human BM.

Fig. 1

Detection of tumor-specific T cells in primary breast cancer patients. a–c Representative results from IFN-γ EliSpot assays with BMTCs from three different individual patients demonstrate the presence (a, c) or absence (b) of tumor antigen-specific T cells tested for recognition of autologous tumor lysate (aut. Tu-L) (a, b) or of HLA-A^*0201-restricted tumor peptides (Hpa, MUC1) (c) as test antigens (black bars) as compared to respective negative control antigens (gray bars) from autologous PBMC lysate (aut. PB-L) or HIV_gag/insulin. White bars spot numbers in wells containing unstimulated TCs or DCs alone. Bars show mean ± SEM of triplicate wells. *Significant (P < 0.05) difference to control group. NS not significant. d Positive EliSpot results are not caused by reduced spot numbers in negative control wells. Mean ± SEM IFN-γ spots in cumulated test or control wells of EliSpot-positive (EliSpot pos.) or EliSpot-negative (EliSpot neg.) patients using autologous tumor lysate or MCF-7 lysate as test antigens (Tu; black bars), compared to the respective negative control antigens autologous PBMC lysate or U937 lysate (control; gray bars). *Significant (P < 0.05) difference between test groups from positive patients and indicated control groups by two-sided Student’s t test; NS not significant

Fig. 2

TC immunity in correlation to clinical disease spread. a–c Proportions of patients with (EliSpot pos., black bars) or without (EliSpot neg., gray bars) BMTCs reactive against MCF-7 or autologous breast tumor lysate according to the absence (M0) or presence (M1) of metastatic disease (a), according to the absence (N0) or presence (N1–3) of lymph node involvement (b) or the absence (CA15-3^norm) or presence (CA15-3^high) of increased serum concentrations of the tumor marker CA15-3 in M0 patients (c). *Significant (P < 0.05) difference between groups as analyzed by Fisher’s exact test (a) or χ² test (b, c); NS not significant. d–f Increased concentrations of CA15-3 in non-metastatic patients containing tumor antigen reactive BMTCs specific for MCF-7 or autologous breast tumor lysate (d) or the HLA-A^*0201-restricted peptides MUC1 (e) or Hpa_16–24 and Hpa_183–191 (f). Patients are grouped according to the presence (+) or absence (−) of respective tumor antigen-specific BMTCs. Mean ± SEM values are shown. *Significant (P < 0.05) difference between groups by two-sided Student’s t test; NS not significant