Langerhans-Type Dendritic Cells Genetically Modified to Express Full-Length Antigen Optimally Stimulate CTLs in a CD4-Dependent Manner

Abstract

Oncoretroviral vectors encoding either full-length Ag or a corresponding immunodominant peptide were expressed in Langerhans-type dendritic cells (LCs) differentiated from CD34+ progenitors. We used human CMV as a model Ag restricted by HLA-A*0201 to define parameters for eventual expression of cancer Ags by LCs for active immunization against tumors. Stimulation by CMVpp65495–503-pulsed LCs, CMVpp65495–503-transduced LCs, and full-length CMVpp65-transduced LCs respectively increased tetramer-reactive T cells with an effector memory phenotype by 10 ± 11, 34 ± 21, and 51 ± 24-fold (p < 0.05) from CMV-seropositive donors. CMV-specific CD8+ CTLs achieved respective frequencies of 231 ± 102, 583 ± 219, and 714 ± 281 spot-forming cells per 105 input cells (p < 0.01) in ELISPOT assays for IFN-γ secretion. LCs expressing full-length Ag stimulated greater lytic activity than either peptide-transduced or peptide-pulsed LCs (p < 0.05), all in the absence of exogenous cytokines. pp65-transduced LCs presenting class I and II MHC-restricted epitopes expanded IFN-γ-secreting CD4+ T cells, whereas pp65495–503-transduced LCs did not. CD4+ T cell numbers even declined after stimulation by pp65495–503 peptide-pulsed LCs. CD4+ T cell depletion confirmed their contribution to the more robust CTL responses. LCs, transduced with a retroviral vector encoding full-length Ag, stimulate potent CTLs directed against multiple epitopes in a CD4+ Th cell-dependent manner.

Primary Human Immunodeficiency Virus Type 1-Specific CD8+T-Cell Responses Induced by Myeloid Dendritic Cells

“…This effect was not related to, or confounded by, antigen-specific activation of the CD4 ϩ T cells, as was demonstrated with purified CD8 ϩ T cells and with HLA A*0201-restricted 9-mer peptides matched with HLA A*0201 haplotype study subjects. A similar helper activity of CD4 ϩ T cells has previously been shown for CD8 ϩ T-cell priming to antigen-loaded adult LC (61). Although initial antigen stimulation via DC is considered sufficient to trigger CD8 ϩ T-cell differentiation, CD4 ϩ T cells are required to induce differentiation of the naïve CD8 ϩ T cells into functional memory cells (3).…”

“…HLA A*0201 tetramers refolded around HIV-1 p17 77-85 (SL9), EBV BMLF1280-288 (GL9), FLU M1 [58][59][60][61][62][63][64][65][66] (GL9), and CMV pp65 495-503 (NV9) were used to stain T cells that were stimulated by the peptide-loaded DC. In some experiments, the T cells were also surface stained with CD3-APC Cy7, CD8-Pacific blue, CD45 RA PE cyanin 7, CCR7-fluorescein isothiocyanate, CD27-PE (BD PharMingen), and tetramer-APC (Beckman Coulter, Fullerton, CA).…”

“…ϩ T cells enhanced the priming of adult donor anti-HIV-1 CD8 ϩ T cells by mature DC, as has previously been demonstrated for priming of neonatal CD8 ϩ T cells (61). We therefore included autologous CD4…”

“…Previous studies have shown that CD4 ϩ T cells are required for optimal CD8 ϩ T-cell priming to antigen-loaded, neonatal LC (61). We therefore next examined whether adult DC matured with CD40L and IFN-␥ required CD4 ϩ T cells for optimal priming of antiviral CD8 ϩ T cells.…”

Recombined CC chemokine ligand 2 into B16 cells induces production of Th2-dominanted cytokines and inhibits melanoma metastasis

“…Traditionally, the polarization of Th1 cells is thought to contribute to cellular immune response and result in the increase of CD8+ cytotoxic T lymphocytes (CTLs); Th2 cell is associated with hormonal immune response and the increase of CD4+ helper T cells (Th) and memory T cells. Th and memory T cells play very important roles in maintaining the activity of CTLs during anti-tumor immune surveillance [14]. It has been reported that injection of Th2 cells into mice effectively repressed the tumor metastasis, increased T cells sensitivity to tumor antigens, and induced effective anti-tumor immune response [15,16].…”