Data from CD20⁺ Tumor-Infiltrating Lymphocytes Have an Atypical CD27⁻ Memory Phenotype and Together with CD8⁺ T Cells Promote Favorable Prognosis in Ovarian Cancer

Abstract

<div>Abstract<p><b>Purpose:</b> Tumor-infiltrating lymphocytes (TIL), in particular CD8<sup>+</sup> T cells and CD20<sup>+</sup> B cells, are strongly associated with survival in ovarian cancer and other carcinomas. Although CD8<sup>+</sup> TIL can mediate direct cytolytic activity against tumors, the role of CD20<sup>+</sup> TIL is poorly understood. Here, we investigate the possible contributions of CD20<sup>+</sup> TIL to humoral and cellular tumor immunity.</p><p><b>Experimental Design:</b> Tumor and serum specimens were obtained from patients with high-grade serous ovarian cancer. CD8<sup>+</sup> and CD20<sup>+</sup> TIL were analyzed by immunohistochemistry and flow cytometry. Immunoglobulin molecules were evaluated by DNA sequencing. Serum autoantibody responses to the tumor antigens p53 and NY-ESO-1 were measured by ELISA.</p><p><b>Results:</b> The vast majority of CD20<sup>+</sup> TIL were antigen experienced, as evidenced by class-switching, somatic hypermutation, and oligoclonality, yet they failed to express the canonical memory marker CD27. CD20<sup>+</sup> TIL showed no correlation with serum autoantibodies to p53 or NY-ESO-1. Instead, they colocalized with activated CD8<sup>+</sup> TIL and expressed markers of antigen presentation, including MHC class I, MHC class II, CD40, CD80, and CD86. The presence of both CD20<sup>+</sup> and CD8<sup>+</sup> TIL correlated with increased patient survival compared with CD8<sup>+</sup> TIL alone.</p><p><b>Conclusions:</b> In high-grade serous ovarian tumors, CD20<sup>+</sup> TIL have an antigen–experienced but atypical CD27<sup>−</sup> memory B-cell phenotype. They are uncoupled from serum autoantibodies, express markers of antigen-presenting cells, and colocalize with CD8<sup>+</sup> T cells. We propose that the association between CD20<sup>+</sup> TIL and patient survival may reflect a supportive role in cytolytic immune responses. <i>Clin Cancer Res; 18(12); 3281–92. ©2012 AACR</i>.</p></div>