Evaluation of CD8+ T-cell frequencies by the Elispot assay in healthy individuals and in patients with metastatic melanoma immunized with tyrosinase peptide
✍ Scribed by Jonathan J. Lewis; Sylvia Janetzki; Susanne Schaed; Katherine S. Panageas; Siqun Wang; Linda Williams; Michael Meyers; Leah Butterworth; Philip O. Livingston; Paul B. Chapman; Alan N. Houghton
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- French
- Weight
- 172 KB
- Volume
- 87
- Category
- Article
- ISSN
- 0020-7136
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✦ Synopsis
The lack of reproducible, quantitative assays for T-cell responses has been a limitation in the development of cancer vaccines to elicit T-cell immunity. We utilized the Elispot assay, which allows a quantitative and functional assessment of T cells directed against specific peptides after only brief in vitro incubations. CD8 ؉ T-cell reactivity was determined with an interferon (IFN)-␥Elispot assay detecting T cells at the single cell level that secrete IFN-␥. We studied both healthy individuals and patients with melanoma. Healthy HLA-A*0201-positive individuals showed a similar mean frequency of CD8 ؉ cells recognizing a tyrosinase peptide, YM-DGTMSQV, when compared with melanoma patients prior to immunization. The frequencies of CD8 ؉ cells recognizing the tyrosinase peptide remained relatively constant over time in healthy individuals. Nine HLA-A*0201-positive patients with stage IV metastatic melanoma were immunized intradermally with the tyrosinase peptide together with the immune adjuvant QS-21 in a peptide dose escalation study with 3 patients per dose group. Two patients demonstrated a significant increase in the frequency of CD8 ؉ cells recognizing the tyrosinase peptide during the course of immunization, from approx. 1/16,000 CD8 ؉ T cells to approx. 1/4,000 in the first patient and from approx. 1/14,000 to approx. 1/2,000 in the second patient. These results demonstrate that modest expansion of peptide-specific CD8 ؉ T cells can be generated in vivo by immunization with peptide plus QS-21 in at least a subset of patients with melanoma. Int.