Quantitation of antigen-reactive T cells in peripheral blood by IFN gamma-ELISPOT assay and chromium-release assay: a four-centre comparative trial

The ELISPOT assay is increasingly being used for the monitoring of the indu ction of antigen-reactive T cells in cancer vaccination trials. In order to evaluate the reliability of T cell frequency analysis with the ELISPOT ass ay, a comparative study was performed in four European laboratories. Six sa mples from healthy subjects were analyzed for the frequency of influenza-re active CD8+ T cells in peripheral blood mononuclear cells (PBMC) by IFN gam ma -ELISPOT assay. In addition, one laboratory determined cytotoxic T cell precursor (CTL) frequencies in these samples by limiting dilution chromium- release assay (LDA), and three laboratories performed a variant of the LDA, the multiple microculture assay (MMA). Consistent frequencies of influenza peptide-reactive T cells were obtained with the ELISPOT assay in all four laboratories. The numbers detected by ELISPOT assay correlated closely with those determined by LDA. In contrast, the frequencies obtained with the MM A differed considerably and showed Little correlation with the other two as says. This study shows that it is possible to use the ELISPOT assay tl, det ermine with reliability antigen-reactive T cells in a multicenter setting. We suggest that this assay may be suitable for monitoring cancer vaccine tr ials. (C) 2000 Elsevier Science B.V. All rights reserved.