Intraepithelial CD8+ tumor-infiltrating lymphocytes and a high CD8+/regulatory T cell ratio are associated with favorable prognosis in ovarian cancer

Abstract

In a recent report, [Zhang et al. (2003) N. Engl. J. Med. 348, 203-213], the presence of CD3+ tumor-infiltrating lymphocytes (TILs) was found to correlate with improved survival in epithelial ovarian cancer. We performed immunohistochemical analysis for TILs and cancer testis antigens in 117 cases of epithelial ovarian cancer. The interrelationship between subpopulations of TILs and expression of cancer testis antigens was investigated, as well as between TILs and overall survival. The median follow-up of the patients was 31 months. Patients with higher frequencies of intraepithelial CD8+ T cells demonstrated improved survival compared with patients with lower frequencies [median = 55 versus 26 months; hazard ratio = 0.33; confidence interval (C.I.) = 0.18-0.60; P = 0.0003]. No association was found for CD3+ TILs or other subtypes of intraepithelial or stromal TILs. However, the subgroups with high versus low intraepithelial CD8+/CD4+ TIL ratios had median survival of 74 and 25 months, respectively (hazard ratio = 0.30; C.I. = 0.16-0.55; P = 0.0001). These results indicate that CD4+ TILs influence the beneficial effects of CD8+ TIL. This unfavorable effect of CD4+ T cells on prognosis was found to be due to CD25+ forkhead box P3 (FOXP3)+ regulatory T cells (Treg; suppressor T cells), as indicated by survival of patients with high versus low CD8+/Treg ratios (median = 58 versus 23 months; hazard ratio = 0.31; C.I. = 0.17-0.58; P = 0.0002). The favorable prognostic effect of intraepithelial CD8+ TILs did not correlate with concurrent expression of NY-ESO-1 or MAGE antigens. We conclude that intraepithelial CD8+ TILs and a high CD8+/Treg ratio are associated with favorable prognosis in epithelial ovarian cancer.

Figures

Fig. 1.

Representative pictures of lymphocyte infiltration in EOC. TILs were observed both in cancer stroma and within cancer epithelium (i.e., intraepithelial). (A) CD20+ TILs frequently form lymphoid aggregates in cancer stroma. (B) CD3+ TILs in a lymphoid aggregate. (Original magnification: ×20). (C) CD3+ TIL distribution in stromal and intraepithelial areas. (D and E) CD8+ (D) and CD4+ (E) TILs in stromal (arrow) and intraepithelial (arrowhead) areas. (F) Treg cells (CD25+FOXP3+) (arrow) were detected by double immunohistochemistry of CD25 (brown) and FOXP3 (red). (G) Triple immunohistochemistry showing heterogenous expression of NY-ESO-1 (brown/arrow) in ovarian cancer with the presence of CD8+ TILs (blue) and CD20+ TILs (red). (Scale bar, 50 μm.)

Fig. 2.

Prognostic significance of TILs in ovarian cancer. (A) Frequency distribution of intraepithelial CD8+ TILs showing a heavier left than right tail of the curve (i.e., did not show a normal distribution curve). The x axis shows the average number of intraepithelial CD8+ TILs, and the y axis shows the number of cases in each class. Cumulative survival time was calculated by the Kaplan–Meier method and analyzed by the log-rank test. High frequency of intraepithelial CD8+ TILs was associated with improved survival (B), whereas the presence or absence of intraepithelial CD3+ TILs was not associated with improved survival using the tertile classification (C) or Zhang et al's (6) classification (D). Intraepithelial CD4+ TILs were also not associated with improved survival (E), but a high intraepithelial CD8+/CD4+ ratio was associated with improved overall survival (F). Treg were not prognostic for survival (G), but a high intraepithelial CD8+/Treg ratio was found to be associated with improved survival (H). Significant results are boxed in blue.