Evidence for in situ expansion of diverse antitumor-specific cytotoxic T lymphocyte clones in a human large cell carcinoma of the lung

We have isolated several cytotoxic T lymphocyte (CTL) clones from lymphocytes infiltrating a human large cell carcinoma (LCC) of the lung. All these clones were found to express a CD3⁺, TCRαβ⁺, CD8⁺, CD4^-, CD28^- phenotype. According to their TCR β chain variable region expression, they were divided in three major groups. The first group, including the majority of the clones, expressed a unique V(β)3-J(β)1.2 TCR. The second group expressed a V(β)22-J(β)1.4 rearrangement and the third group, including only two clones, expressed a V(β)8-J(β)1.5 TCR. Functional studies showed that all the CTL clones mediated a high cytotoxic activity against the autologous tumor cell line. While the V(β)3⁺ clones showed a weak lysis against few allogeneic non-small cell lung cancer (NSCLC) tumor cell lines, V(β)8⁺ and V(β)22⁺ T cell clones were able to kill a panel of allogeneic NSCLC tumor cell lines. Cytotoxicity-blocking experiments using specific mAb indicated that, while the V(β)3⁺ and V(β)22⁺ CTL clones were HLA-A2 restricted, the V(β)8⁺ clones appeared HLA-B or -C restricted. TCR transcripts expressed in the cloned cells were determined by CDR3 size and sequence analyses, and compared to those present in fresh tumor tissue. Interestingly, our studies demonstrated that the CTL clones identified in vitro were selectively expanded in vivo at the tumor site as compared to autologous peripheral blood lymphocytes. These results further provide evidence that an immune response may take place in NSCLC and that effector T cells may contribute to tumor regression.