title: Frequency of cytotoxic T lymphocyte precursors (CTLp) interacting with autologous tumor via the T-cell receptor: limiting dilution analysis of specific CTLp in peripheral blood and tumor-invaded lymph nodes of melanoma patients.
abstract: The frequencies of cytotoxic T-lymphocyte precursors (CTLp) that lyse autologous tumor by a T-cell receptor (TCR)-dependent mechanism (specific CTLp) were evaluated by limiting dilution analysis (LDA) using lymphocytes from peripheral blood (PBL) and from surgically resected, tumor-invaded lymph nodes (LNL) in 9 melanoma patients. The frequency of specific CTLp was determined in PBLs and/or LNIs of all patients by a modified LDA assay, enabling us to measure lytic activity on the autologous tumor that could be significantly inhibited by an anti-CD3 monoclonal antibody (MAb). This assay allowed us to detect frequencies of specific CTLp ranging from 1/720 to 1/32,037 in peripheral blood and from 1/328 to 1/22,061 in tumor-invaded lymph nodes. These frequencies indicated that lymphoid populations from PBLs or LNLs of melanoma patients may contain as low as 30 to as much as 3,000 specific CTLp/10(6) lymphocytes. In addition, comparison of wells containing specific CTLp with those showing no inhibition by anti-CD3 MAb indicated that specific CTLp represent between 3 and 88% of all precursors with lytic activity on the tumor. In 6 of 9 patients, no marked differences between PBLs and LNIs in specific CTLp frequencies were found. A 10-fold increase of specific CTLp, in comparison to PBL and LNL, was found only in lymphocytes isolated from a subcutaneous metastasis of one patient. Our results indicate that CTLp interacting with autologous tumor by a TCR-dependent mechanism exist in PBL and LNL of most melanoma patients, although a wide variation in their absolute number is evident among different patients.
authors.affiliation: Division of Experimental Oncology D, Istituto Nazionale Tumori, Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Mazzocchi
authors.forename: F
authors.initials: F
authors.lastname: Belli
authors.forename: L
authors.initials: L
authors.lastname: Mascheroni
authors.forename: C
authors.initials: C
authors.lastname: Vegetti
authors.forename: G
authors.initials: G
authors.lastname: Parmiani
authors.forename: A
authors.initials: A
authors.lastname: Anichini
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008213:Lymphocyte Activation; D016131:Lymphocyte Subsets; D008297:Male; D008545:Melanoma / Q000097:blood* / Q000473:pathology* / Q000556:secondary; D008875:Middle Aged; D010641:Phenotype; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D012680:Sensitivity and Specificity; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology*
chemical_list: D011948:Receptors, Antigen, T-Cell