title: Natural cell-mediated cytotoxicity (NCMC) against NK-sensitive tumours in vitro by murine spleen Ly-6C+ natural T cells.
abstract: Ly-6C+ cells constitute 13 +/- 3% of freshly isolated (CBA x C57BL/6)F1 mouse spleen leukocytes. Three distinct populations were identified: CD3 epsilon +NK-1.1- conventional T cells (6%), CD3 epsilon -NK-1.1- granulocytes (5%) and CD3 epsilon +NK-1.1+ T cells (approximately 2%). The CD3 epsilon +NK-1.1+ cells displayed a predominantly large granular leukocyte morphology and were the only Ly-6C+ cell subset identified by MAb 2B6-F2 to spontaneously lyse the NK-sensitive YAC-1 tumour in vitro. On further phenotypic analysis, these cells co-expressed high levels of TCRV beta 8.1/8.2 and CD11b, moderate levels of CD90 and low levels of CD4 or CD8. The removal of CD4+ and CD8+ cells prior to Ly-6C+ cell sorting showed that it was the CD4-CD8- double-negative (DN) CD3 epsilon +NK-1.1+ T-cell subset which was responsible for killing YAC-1. These results indicate that we have identified a DN Ly-6C+ subset of the recently designated NK-1.1+TCR alpha beta low natural T (NT) cells, which are capable of natural cell-mediated cytotoxicity (NCMC) against the NK-sensitive YAC-I tumour in vitro. Additionally, these cells mediated the in vitro killing of 2 further NK-sensitive tumours, murine B16 melanoma and human Jurkat T lymphoma. YAC-1 and Jurkat expressed Fas and were susceptible to anti-Fas MAb or rhuman Fas ligand (rhFasL)-induced lysis. Furthermore, anti-human Fas MAb M3 was shown to block sorted Ly-6C+ splenocyte in vitro killing of Jurkat. In contrast, B16 did not express cell-surface Fas and was resistant to anti-Fas MAb-induced lysis. Taken together, these results show that not only do Ly-6C+ NT cells kill NK-sensitive tumours in vitro but they mediate this activity via multiple cytotoxic mechanisms including Fas.
authors.affiliation: Discipline of Surgical Science, Faculty of Medicine and Health Science, University of Newcastle, Newcastle, NSW, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Martiniello
authors.forename: R C
authors.initials: RC
authors.lastname: Burton
authors.forename: Y C
authors.initials: YC
authors.lastname: Smart
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000378:metabolism; D000950:Antigens, Ly / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007111:Immunity, Cellular / Q000276:immunology*; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D010641:Phenotype; D013154:Spleen / Q000166:cytology / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000950:Antigens, Ly