Differential gene expression profiles in a human T-cell line stimulated with a tumor-associated self-peptide versus an enhancer agonist peptide.

Abstract

Previous studies have shown that a specific 9-mer amino acid epitope (designated CAP-1) of the human "self" tumor-associated carcinoembryonic antigen can be used to stimulate CD8+ T cells from peripheral blood mononuclear cells of carcinoma patients vaccinated with pox vector-based carcinoembryonic antigen vaccines. A T-cell receptor agonist epitope of CAP-1 (designated CAP1-6D) has been shown to enhance the stimulation of T cells over levels obtained using CAP-1. The purpose of this study was to analyze gene expression profiles in T cells stimulated with the native CAP-1 versus the agonist CAP1-6D peptide. Microarray analyses were conducted to analyze differential gene expression profiles of a T-cell line stimulated with native versus agonist peptides. Numerous genes and gene clusters are identified as differentially expressed as a consequence of stimulation with the agonist peptide versus the native peptide; two genes, however, stand out in magnitude: the chemokine lymphotactin and granzyme B. In particular, lymphotactin expression is >12 times more pronounced in agonist-stimulated T cells. An ELISA assay was developed that confirmed marked lymphotactin secretion in T cells when stimulated with the agonist versus the native peptide. A chemotaxis assay also demonstrated the biological activity of the lymphotactin produced. To our knowledge, these are the first studies of gene expression profiles of a defined T-cell line in response to stimulation with a defined antigen. They are also the first to compare, via cDNA microarray, responses of a T-cell line to (a) a tumor-associated self-antigen and (b) a native epitope versus an agonist epitope.