Tumor Rejection After Direct Costimulation of CD8 ⁺ T Cells by B7-Transfected Melanoma Cells

TLDR

Many tumors are immunogenic yet fail to elicit effective anti‑tumor immunity because they lack sufficient costimulatory signals for T‑cell activation. B7 expression on melanoma cells triggers CD8⁺‑T‑cell–mediated rejection, demonstrating that costimulation enables tumor cells to present antigen effectively and be eradicated in vivo.

Abstract

A variety of tumors are potentially immunogenic but do not stimulate an effective anti-tumor immune response in vivo. Tumors may be capable of delivering antigen-specific signals to T cells, but may not deliver the costimulatory signals necessary for full activation of T cells. Expression of the costimulatory ligand B7 on melanoma cells was found to induce the rejection of a murine melanoma in vivo. This rejection was mediated by CD8 + T cells; CD4 + T cells were not required. These results suggest that B7 expression renders tumor cells capable of effective antigen presentation, leading to their eradication in vivo.