Identification of a T-cell receptor from a therapeutic murine T-cell clone

Tumor-infiltrating lymphocytes (TIL) have been successfully used for the treatment of metastatic malignancies in clinical trials and in experimental animal models. Tumor-specific reactivity by TIL is mediated via receptors expressed on the surface of T cells (TcRs), which recognize tumor-associated antigens (TAA) presented in the context of MHC molecules on the surface of tumor cells. The current study was performed to identify the TcR alpha and beta chains from a tumor-specific therapeutic TIL clone that can be used to develop a preclinical animal model for genetically modifying lymphocytes and hematopoietic progenitors with TcR genes. TIL 205 was generated from a subcutaneous implant of MCA-205 fibrosarcoma and at 21 days was cloned by limiting dilution. TIL clone 8, obtained from a culture seeded at one cell/well, mediated specific lysis and specific secretion of gamma-interferon to MCA-205 and WP6, a subclone of MCA 205. No reactivity was observed against other syngeneic sarcoma lines. Anchor polymerase chain reaction analysis determined that antigen recognition by clone 8 was mediated by a TcR consisting of V alpha 3/J alpha 27 and V beta 8.2/D beta 2.1/D beta 2.4. Immunofluorescent staining with V beta subfamily specific monoclonal antibodies revealed that > 95% of the T cells in TIL clone 8 expressed V beta 8.2, confirming that TIL clone 8 was indeed a clone. In contrast, approximately 30% of the T cells in the parental TIL 205 expressed V beta 8.2. The transfer of as few as 500,000 TIL clone 8 cells in conjunction with the systemic administration of recombinant human interleukin-2 mediated regression of established 3-day WP6 lung metastases. Thus, clone 8 recognizes a biologically relevant tumor rejection antigen, making the V alpha 3/J alpha 27-V beta 8.2/D beta 2.1/J beta 2.4 TcR isolated from this clone useful as a probe for cloning the tumor-rejection antigen in the WP6 tumor as well as modeling, in mice, the TcR-based gene therapies being developed for humans.