Identification of DC-SIGN, a novel dendritic cell-specific ICAM-3 receptor that supports primary immune responses

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Initiating primary immune responses requires contact between dendritic cells (DCs) and resting T cells.
• Intercellular adhesion molecules (ICAMs) play critical roles in cell-cell interactions within the immune system.

Purpose of the Study:

• To investigate the role of ICAM-3 on resting T cells in the initial contact with DCs.
• To identify the specific DC receptor responsible for binding ICAM-3 and mediating T cell adhesion.

Main Methods:

• Utilized in vitro and in vivo models of DC-T cell interaction.
• Employed antibody-based inhibition assays to assess the functional role of DC-SIGN.
• Investigated the binding affinity between ICAM-3 and DC-SIGN.

Main Results:

• Identified DC-SIGN, a C-type lectin highly expressed on DCs, as a high-affinity receptor for ICAM-3.
• Demonstrated that DC-SIGN mediates transient adhesion between T cells and DCs.
• Showed that antibodies blocking DC-SIGN inhibit DC-induced proliferation of resting T cells.

Conclusions:

• DC-SIGN is a key mediator of the initial contact between T cells and DCs.
• DC-SIGN binding to ICAM-3 stabilizes the DC-T cell conjugate, facilitating T cell receptor engagement and subsequent T cell activation.
• These findings highlight DC-SIGN's critical role in initiating adaptive immune responses.