T-cell receptor repertoires of tumor-infiltrating lymphocytes after hyperthermia using functionalized magnetite nanoparticles

Aim: Accumulating evidence has indicated that hyperthermia using magnetite nanoparticles induces antitumor immunity. This study investigated the diversity of T-cell receptors (TCRs) in tumor-infiltrating lymphocytes after hyperthermia using magnetite nanoparticles.Materials & methods: Functionalized magnetite nanoparticles, N-propionyl-4-S-cysteaminylphenol (NPrCAP)/magnetite, were synthesized by conjugating the melanogenesis substrate NPrCAP with magnetite nanoparticles. NPrCAP/magnetite nanoparticles were injected into B16 melanomas in C57BL/6 mice, which were subjected to an alternating magnetic field for hyperthermia treatment. Results: Enlargement of the tumor-draining lymph nodes was observed after hyperthermia. The TCR repertoire was restricted in tumor-infiltrating lymphocytes, and expansion of Vβ11⁺ T cells was preferentially found. DNA sequences of the third complementaritydetermining regions revealed the presence of clonally expanded T cells. Conclusion: These results indicate that the T-cell response in B16 melanomas after hyperthermia is dominated by T cells directed toward a limited number of epitopes and that epitope-specific T cells frequently use a restricted TCR repertoire.