Melanoma Sequentially Suppresses Different DC Subsets in the Sentinel Lymph Node, Affecting Disease Spread and...

Area of Science:

• Immunology
• Oncology
• Dendritic Cell Biology

Background:

• Melanoma utilizes immune suppression to advance tumor progression and metastasis.
• Understanding immune cell dynamics in sentinel lymph nodes (SLNs) is crucial for predicting melanoma outcomes.

Purpose of the Study:

• To investigate the impact of melanoma on dendritic cell (DC) and T-cell subsets within SLNs.
• To determine the clinical significance of these immune cell alterations in relation to melanoma recurrence and survival.

Main Methods:

• Analysis of four conventional DC subsets, plasmacytoid DCs, CD4+, CD8+, and regulatory T cells (Tregs) via flow cytometry in 36 melanoma SLNs from 28 patients.
• Correlation of immune cell data with clinical parameters, including Breslow thickness and lymph node metastasis.
• Longitudinal follow-up to assess local and distant melanoma recurrence, with a median of 75 months.

Main Results:

• In early-stage melanoma (I-II), increased tumor thickness correlated with suppressed migratory CD1a+ DC subsets.
• Lymph node-resident DCs and T cells were affected only after SLN metastasis.
• In advanced melanoma (Stage III), altered CD4:CD8 ratios and increased Tregs were observed.
• Reduced migratory DC subsets predicted local recurrence, while impaired LN-resident DC maturation predicted distant recurrence and poorer survival.

Conclusions:

• Melanoma-induced suppression of migratory DCs in SLNs precedes local spread.
• Suppression of LN-resident DCs follows regional spread and precedes distant metastasis.
• Targeting both migratory and LN-resident DCs presents a potential immunotherapeutic strategy to prevent melanoma recurrence and dissemination.