In vivo expression of natural killer cell inhibitory receptors by human melanoma-specific cytolytic T lymphocytes.
Speiser DE., Pittet MJ., Valmori D., Dunbar R., Rimoldi D., Liénard D., MacDonald HR., Cerottini JC., Cerundolo V., Romero P.
Natural killer (NK) receptor signaling can lead to reduced cytotoxicity by NK cells and cytolytic T lymphocytes (CTLs) in vitro. Whether T cells are inhibited in vivo remains unknown, since peptide antigen-specific CD8(+) T cells have so far not been found to express NK receptors in vivo. Here we demonstrate that melanoma patients may bear tumor-specific CTLs expressing NK receptors. The lysis of melanoma cells by patient-derived CTLs was inhibited by the NK receptor CD94/NKG2A. Thus, tumor-specific CTL activity may be decreased through NK receptor triggering in vivo.