title: Tumor-specific CD4+ T lymphocytes from cancer patients are required for optimal induction of cytotoxic T cells against the autologous tumor.
abstract: This study focuses on the specific CD4+ T cell requirement for optimal induction of cytotoxicity against MHC class II negative autologous tumors (AuTu) collected from patients with various types of cancer at advanced stages. CD4+ T cells were induced in cultures of cancer patients' malignant effusion-associated mononuclear cells with irradiated AuTu (mixed lymphocyte tumor cultures (MLTC)) in the presence of recombinant IL-2 and recombinant IL-7. Tumor-specific CD4+ T cells did not directly recognize the AuTu cells, but there was an MHC class II-restricted cross-priming by autologous dendritic cells (DCs), used as APC. CD8+ CTL, also induced during the MLTC, lysed specifically AuTu cells or DCs pulsed with AuTu peptide extracts (acid wash extracts (AWE)) in an MHC class I-restricted manner. Removal of CD4+ T cells or DCs from the MLTC drastically reduced the CD8+ CTL-mediated cytotoxic response against the AuTu. AWE-pulsed DCs preincubated with autologous CD4+ T cells were able, in the absence of CD4+ T cells, to stimulate CD8+ T cells to lyse autologous tumor targets. Such activated CD8+ T cells produced IL-2, IFN-gamma, TNF-alpha, and GM-CSF. The process of the activation of AWE-pulsed DCs by CD4+ T cells could be inhibited with anti-CD40 ligand mAb. Moreover, the role of CD4+ T cells in activating AWE-pulsed DCs was undertaken by anti-CD40 mAb. Our data demonstrate for the first time in patients with metastatic cancer the essential role of CD4+ Th cell-activated DCs for optimal CD8+ T cell-mediated killing of autologous tumors and provide the basis for the design of novel protocols in cellular adoptive immunotherapy of cancer, utilizing synthetic peptides capable of inducing T cell help in vivo.
authors.affiliation: Cancer Immunology and Immunotherapy Center, Saint Savas Cancer Hospital, Athens, Greece. baxevani@ath.forthnet.gr
authors.forename: C N
authors.initials: CN
authors.lastname: Baxevanis
authors.forename: I F
authors.initials: IF
authors.lastname: Voutsas
authors.forename: O E
authors.initials: OE
authors.lastname: Tsitsilonis
authors.forename: A D
authors.initials: AD
authors.lastname: Gritzapis
authors.forename: R
authors.initials: R
authors.lastname: Sotiriadou
authors.forename: M
authors.initials: M
authors.lastname: Papamichail
mesh_terms: D000368:Aged; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002450:Cell Communication / Q000276:immunology; D002457:Cell Extracts / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D005260:Female; D006801:Humans; D016219:Immunotherapy, Adoptive / Q000379:methods; D008213:Lymphocyte Activation / Q000276:immunology*; D007959:Lymphocyte Culture Test, Mixed; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000276:immunology* / Q000473:pathology / Q000628:therapy*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014269:Trifluoroacetic Acid; D014407:Tumor Cells, Cultured
chemical_list: D002457:Cell Extracts; D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D014269:Trifluoroacetic Acid