Monitoring of CD4+ and CD8+ T-cell responses after dendritic cell-based immunotherapy using CFSE dye dilution analysis

CFSE dye dilution analysis and [H-3] thymidine incorporation were used side by side to assess proliferative responses of peripheral blood mononuclear cells (PBMCs) after vaccination of renal cell carcinoma patients (n=6) with antigen-loaded dendritic cells. Immune responses against the control antigen keyhole limpet hemocyanin (KLH) were induced in all patients. While [H-3] thymidine incorporation revealed a 4 to 977-fold increase in KLH-induced proliferation (mean:209-fold), CFSE-labeling experiments demonstrated that the KLH-responsive population of postvaccination PBMCs represented 7-53% (mean:23%). Combining CFSE-labeling with T-cell subset analysis confirmed the presence of CD4(+) KLH-reactive T cells but also revealed a substantial population of CD8(+) KLH-reactive T cells in one patient as well as minor populations of CD8(+) KLH-reactive T cells in three other patients. Our data indicate that CFSE dye dilution analysis is a valuable tool for immune monitoring after dendritic cell vaccination.