A modified human ELISPOT assay to detect specific responses to primary tumor cell targets.
BACKGROUND: The desired outcome of cancer vaccination is to induce a potent T cell response which can specifically recognize and eliminate autologous tumor cells in vivo. Accordingly, immunological assays that demonstrate recognition of native tumor cells (tumor-specific) may be more clinically relevant than assays that demonstrate recognition of tumor protein or peptide (antigen-specific). METHODS: Towards this goal, we adapted the IFN-gamma ELISPOT assay to measure immune responses against autologous primary tumor cells in vaccinated cancer patients. As a model system to develop the assay, we utilized peripheral blood mononuclear cells (PBMC) directly isolated from follicular lymphoma patients vaccinated with tumor-derived idiotype protein. RESULTS: After optimizing several variables, we demonstrated that the modified IFN-gamma ELISPOT assay could be used to reliably and reproducibly determine the tumor-reactive T cell frequency in the PBMC of these patients. The precursor frequency of tumor-reactive T cells was significantly higher in the postvaccine PBMC, compared with prevaccine samples in all patients tested. Furthermore, the specificity of these T cells was established by the lack of reactivity against autologous normal B cells. CONCLUSIONS: These results demonstrate the feasibility of quantitating tumor-specific T cell responses when autologous, primary tumor cells are available as targets.
Malyguine
Anatoli
A
Laboratory of Cell-Mediated Immunity, SAIC-Frederick, Inc, National Cancer Institute at Frederick, Frederick, MD 21702 USA. amalyguine@ncifcrf.gov
Strobl
Susan L
SL
Shafer-Weaver
Kimberly A
KA
Ulderich
Tracy
T
Troke
Angela
A
Baseler
Michael
M
Kwak
Larry W
LW
Neelapu
Sattva S
SS