Biomedical subjects

Thierry Boon

Publications and source records attributed to Thierry Boon.

40 records · Page 3Linked to original sources

PubMed2002

A reversible functional defect of CD8+ T lymphocytes involving loss of tetramer labeling.

We have observed that human CTL clones lose their specific cytolytic activity and cytokine production under certain stimulation conditions, while retaining an antigen-dependent growth pattern. These inactive CTL simultaneously lose their labeling by an HLA-peptide tetramer, even though the amount of TCR-CD3 at their surface is not reduced. The tetramer-negative cells recover tetramer staining and cytolytic activity after stimulation with tumor cells in the presence of a supernatant of activated lymphocytes. Our results suggest the existence of a new type of functional defect of CTL. They also indicate that tetramers may fail to reveal some CTL bearing the relevant TCR, even when such functionally arrested CTL retain the potential to participate in immune responses because their defect is reversible.

Antigens, Neoplasm↗

PubMed2002

Cytolytic T-cell responses of cancer patients vaccinated with a MAGE antigen.

'Cancer-germline' genes such as the MAGE gene family are expressed in many tumors and in male germline cells but not in normal tissues. They encode shared tumor-specific antigens, which have been used in therapeutic vaccination trials of metastatic melanoma patients. To establish whether there is a correlation between tumoral regressions and T-cell responses against the vaccine antigen, we evaluated the responses of patients vaccinated with a MAGE-3 antigenic peptide or a recombinant virus coding for the peptide. Blood lymphocytes were stimulated with antigenic peptide followed by detection with tetramer, T-cell cloning, and TCR analysis. In 4/9 regressor patients and in 1/14 progressors we found a low level, usually monoclonal cytolytic T lymphocyte response against the MAGE-3 peptide.

Antigens, Neoplasm↗

PubMed2002

Tumor-specific shared antigenic peptides recognized by human T cells.

The first tumor-specific shared antigens and the cancer-germline genes that code for these antigens were identified with antitumor cytolytic T lymphocytes obtained from cancer patients. A few HLA class I-restricted antigenic peptides were identified by this 'direct approach'. A large set of additional cancer-germline genes have now been identified by purely genetic approaches or by screening tumor cDNA expression libraries with the serum of cancer patients. As a result, a vast number of sequences are known that can code for tumor-specific shared antigens, but most of the encoded antigenic peptides have not yet been identified. We review here recent 'reverse immunology' approaches for the identification of new antigenic peptides. They are based on in vitro stimulation of naive T cells with dendritic cells that have either been loaded with a cancer-germline protein or that have been transduced with viruses carrying cancer-germline coding sequences. These approaches have led to the identification of many new antigenic peptides presented by class I or class II molecules. We also describe some aspects of the processing and presentation of these antigenic peptides.

Amino Acid Sequence↗

PubMed2002

DNA microarray to monitor the expression of MAGE-A genes.

BACKGROUND: The MAGE-A genes encode antigens that are of particular interest for antitumor immunotherapy because they are strictly tumor specific and are shared by many tumors. We developed a rapid method to identify the MAGE-A genes expressed in tumors. METHODS: A low-density DNA microarray was designed to discriminate between the 12 MAGE-A cDNAs amplified by PCR with only one pair of consensus primers. The assay involved reverse transcription of total RNA with oligo(dT) primer, followed by PCR amplification and hybridization on a microarray. Amplification in the presence of Biotin-16-dUTP allowed subsequent detection of the amplicons on the microarray carrying 12 capture probes, each being specific for a MAGE-A gene. Probe-amplicon hybrids were detected by a streptavidin-based method. RESULTS: PCR conditions were optimized for low detection limits and comparable amplification efficiencies among all MAGE-A nucleotide sequences. The microarray assay was validated with a panel of 32 samples, by comparison with well-established reverse transcription-PCR assays relying on amplification with primers specific for each gene. Virtually identical results were obtained with both methods, except for MAGE-A3 and MAGE-A5. Detection of MAGE-A5 was more sensitive with the microarray assay. Detection of MAGE-A3 was hampered by the presence of MAGE-A6, which is 98% identical: the MAGE-A3 capture probe cross-hybridized with MAGE-A6 amplicons because these sequences differed by only a single base. CONCLUSIONS: This post-PCR microarray assay could be useful to evaluate MAGE expression in tumors before therapeutic vaccinations with MAGE-A gene products.

Antigens, Neoplasm↗