Mature dendritic cells boost functionally superior CD8+ T-cell in humans without foreign helper epitopes
Madhav V. Dhodapkar, … , Ralph M. Steinman, Nina Bhardwaj
Madhav V. Dhodapkar, … , Ralph M. Steinman, Nina Bhardwaj
Published March 15, 2000
Citation Information: J Clin Invest. 2000;105(6):R9-R14. https://doi.org/10.1172/JCI9051.
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Mature dendritic cells boost functionally superior CD8+ T-cell in humans without foreign helper epitopes

Abstract

We have recently shown that a single injection of mature, antigen-pulsed, human dendritic cells (DCs) rapidly elicits CD4+ and CD8+ T-cell immunity in vivo. The DCs were pulsed with 2 foreign proteins, keyhole limpet hemocyanin (KLH) and tetanus toxoid (TT), as well as an HLA A2.1-restricted influenza matrix peptide (MP). Responses to all 3 antigens peaked at 30–90 days after immunization and declined thereafter. To determine if the foreign helper proteins (TT and KLH) were essential for CD8+ T-cell responses to the viral peptide, we reinjected 3 of the HLA-2.1 subjects with mature DCs pulsed with MP alone. All 3 volunteers showed a rapid boost in MP-specific immunity, and freshly sampled blood from 1 contained cytolytic T cells. In all 3 subjects, CD8+ T-cell responses to booster DCs were faster and of greater magnitude than the responses to the first DC injection. Importantly, the T cells that proliferated after booster DC treatment secreted interferon-γ upon challenge with much lower doses of viral peptide than those elicited after the first injection, indicating a higher functional avidity for the ligand. These data begin to outline the kinetics of T-cell immunity in response to DCs and demonstrate that booster injections of mature DCs enhance both qualitative and quantitative aspects of CD8+ T-cell function in humans.

Authors

Madhav V. Dhodapkar, Joseph Krasovsky, Ralph M. Steinman, Nina Bhardwaj

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Enhancement of antigen-specific CD8+ T cells in vivo. (a–d) Kinetics of ...
Enhancement of antigen-specific CD8+ T cells in vivo. (a–d) Kinetics of antigen-specific CD8+ T cells following DC injection(s). MP-specific interferon-γ–producing T cells in freshly isolated uncultured T cells were quantified using an ELISPOT assay (triangles). Results are shown as the number of spot-forming cells (SFC)/2 × 105 PBMC. MP-specific CTLs were quantified after 7-day coculture with MP-pulsed mature DCs (DC/T cell ratio 30:1). Data shown are percent of MP-specific lysis at each time point (effector/target [E/T] ratio 20:1) after subtracting lysis with unpulsed T2 targets and that using unpulsed DCs (circles). SEM < 25%. Arrows indicate the timing of DC injections. The subjects were: a, P4; b, P5; c, P6; and d, P1. (e) Detection of circulating lytic effectors after booster DC injection. Freshly isolated bulk PBMCs of a study subject (P4) from before injection and 7 days after booster DC injections 1 and 2 were directly tested for the presence of MP-specific lytic effectors using MP-pulsed T2 cells as targets at varying E/T ratios. Data shown are percent of MP-specific lysis after subtracting lysis of unpulsed T2 cells. (f) Enhancement of MP-specific IFN-γ–producing T cells after booster DC injection, recall ELISPOT assay. Cryopreserved PBMCs from before (pre) and 30 or 120 days after booster DC injection were thawed together and cocultured for 7 days with freshly generated mature DCs (DC/PBMC ratio 1:30), either unpulsed, DC(–), or pulsed with 1 μg/mL MP, DC (MP), without exogenous cytokines. On day 7, T cells were either left unstimulated or restimulated by the addition of 10 μg/mL MP peptide and transferred to an ELISPOT plate. MP-specific IFN-γ–producing T cells were quantified using a 16-hour ELISPOT assay. SEM < 30%.