In vivo selective expansion of a tumour-specific cytotoxic T-cell clone derived from peripheral blood of a melanoma patient after vaccination with gene-modified autologous tumour cells

Melanoma-specific cytotoxic T lymphocytes (CTL) can be generated from perip heral blood lymphocytes (PBL) by mixed lymphocyte-tumour cell cultures. Ana lysis of CTL precursor frequencies in peripheral blood of melanoma patients is generally used for immunomonitoring purposes to evaluate vaccination ef ficacy. At present, it is unclear whether PBL-derived CTL generated in vitr o are indicative of an anti-tumour immune response in vivo. Three tumour-sp ecific human leucocyte antigen (HLA)-B/C-restricted CTL clones were derived from peripheral blood of a melanoma patient immunized with interleukin-7 ( IL-7) gene-modified tumour cells. CTL clones differing in their T-cell rece ptor-gamma (TCR gamma) rearrangement produced interferon-gamma, IL-4 and/or IL-10. On the basis of their unique TCR gamma gene rearrangements clone-sp ecific primers were generated for detection of clone-specific DNA by polyme rase chain reaction. One CTL clone (E5) of the three was found to be select ively expanded in one of seven metastases obtained at autopsy, as determine d by Southern blot hybridization. However, the presence of E5 in only one o f seven metastases at death indicates that the in vivo accumulation of the specific CTL clone was not sufficient to contain tumour progression. Nevert heless, our data support the proposition that analysis of anti-tumour activ ity of PBL-derived CTLs may reflect an anti-tumour immune response in vivo.