Mature dendritic cells boost functionally superior CD8(+) T-cell in humans without foreign helper epitopes

Area of Science:

• Immunology
• Cellular immunology
• Vaccinology

Background:

• Mature dendritic cells (DCs) pulsed with antigens can elicit T-cell immunity.
• Previous studies showed that a single DC injection induces CD4(+) and CD8(+) T-cell responses to foreign proteins and viral peptides.

Purpose of the Study:

• To determine if foreign helper proteins are essential for CD8(+) T-cell responses to viral peptides.
• To assess the impact of booster injections of mature DCs on T-cell immunity.
• To characterize the kinetics and functional avidity of T-cell responses following DC immunization.

Main Methods:

• Human subjects received injections of mature DCs pulsed with keyhole limpet hemocyanin (KLH), tetanus toxoid (TT), and an influenza matrix peptide (MP).
• Some subjects received a subsequent injection of DCs pulsed with MP alone.
• T-cell responses, including proliferation and cytolytic activity, were measured.
• Functional avidity was assessed by interferon-gamma secretion upon challenge with varying peptide doses.

Main Results:

• Responses to all antigens peaked at 30-90 days post-immunization and subsequently declined.
• Re-injection with DCs pulsed with MP alone rapidly boosted MP-specific immunity in all subjects.
• Booster DC injections led to faster and greater magnitude CD8(+) T-cell responses compared to the initial injection.
• T cells from boosted subjects exhibited higher functional avidity, secreting interferon-gamma at lower viral peptide concentrations.

Conclusions:

• Foreign helper proteins are not essential for eliciting CD8(+) T-cell responses to viral peptides using DCs.
• Booster injections of mature DCs enhance both qualitative and quantitative aspects of human CD8(+) T-cell function.
• These findings provide insights into the kinetics of DC-induced T-cell immunity and the benefits of booster immunization.