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Clonal expansions of 6‐thioguanine resistant T lymphocytes in the blood and tumor of melanoma patients
Author(s) -
Albertini Mark R.,
Macklin Michael D.,
Zuleger Cindy L.,
Newton Michael A.,
Judice Stephen A.,
Albertini Richard J.
Publication year - 2008
Publication title -
environmental and molecular mutagenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1
H-Index - 87
eISSN - 1098-2280
pISSN - 0893-6692
DOI - 10.1002/em.20417
Subject(s) - biology , t cell receptor , microbiology and biotechnology , complementarity determining region , melanoma , t cell , mutant , clone (java method) , somatic cell , cancer research , immunology , immune system , gene , genetics , antibody , monoclonal antibody
The identification of specific lymphocyte populations that mediate tumor immune responses is required for elucidating the mechanisms underlying these responses and facilitating therapeutic interventions in humans with cancer. To this end, mutant hypoxanthine‐guanine phosphoribosyltransferase ( HPRT ) deficient ( HPRT ‐) T‐cells were used as probes to detect T‐cell clonal amplifications and trafficking in vivo in patients with advanced melanoma. Mutant T‐cells from peripheral blood were obtained as clonal isolates or in mass cultures in the presence of 6‐thioguanine (TG) selection and from tumor‐bearing lymph nodes (LNs) or metastatic melanoma tissues by TG‐selected mass cultures. Nonmutant (wild‐type) cells were obtained from all sites by analogous means, but without TG selection. cDNA sequences of the T‐cell receptor (TCR) beta chains (TCR‐β), determined directly (clonal isolates) or following insertion into plasmids (mass cultures), were used as unambiguous biomarkers of in vivo clonality of mature T‐cell clones. Clonal amplifications, identified as repetitive TCR‐β V‐region, complementarity determining region 3 (CDR3), and J‐region gene sequences, were demonstrated at all sites studied, that is, peripheral blood, LNs, and metastatic tumors. Amplifications were significantly enriched among the mutant compared with the wild‐type T‐cell fractions. Importantly, T‐cell trafficking was manifested by identical TCR‐β cDNA sequences, including the hypervariable CDR3 motifs, being found in both blood and tissues in individual patients. The findings described herein indicate that the mutant T‐cell fractions from melanoma patients are enriched for proliferating T‐cells that infiltrate the tumor, making them candidates for investigations of potentially protective immunological responses. Environ. Mol. Mutagen., 2008. Published 2008 Wiley‐Liss, Inc.