Subcultured human endothelial cells can function independently as fully competent antigen-presenting cells

Area of Science:

• Immunology
• Cell Biology
• Vascular Biology

Background:

• Antigen-presenting cells (APCs) are crucial for initiating immune responses.
• While macrophages and dendritic cells are known APCs, other cell types like endothelial cells (ECs) have been investigated.
• Previous studies faced challenges in definitively proving ECs' APC capabilities due to potential macrophage contamination.

Purpose of the Study:

• To provide definitive evidence that human endothelial cells (ECs) can independently function as antigen-presenting cells.
• To investigate the antigen-presenting capacity of subcultured human ECs.
• To differentiate EC antigen presentation from that of contaminating macrophages.

Main Methods:

• Isolation and serial subculture of human umbilical vein ECs for up to 8 months.
• Assessment of EC morphology and Factor VIII-related antigen expression via immunofluorescence.
• Testing antigen presentation of subcultured ECs to macrophage-depleted T cells using particulate and soluble antigens.
• Utilizing monoclonal antibodies (anti-HLA-DR, anti-HLA-DS, anti-Mac-120) to analyze antigen presentation pathways.

Main Results:

• Subcultured ECs maintained characteristic morphology and Factor VIII-related antigen expression.
• ECs demonstrated antigen presentation capability equivalent to freshly isolated cells, even after extensive subculturing (up to 18th subculture).
• Monoclonal antibodies targeting HLA-DR and HLA-DS inhibited antigen presentation by both macrophages and ECs.
• The macrophage-specific antibody Mac-120 inhibited macrophage antigen presentation but not EC antigen presentation.

Conclusions:

• Human endothelial cells (ECs) are independently capable of functioning as fully competent antigen-presenting cells.
• ECs present antigens to T cells effectively, irrespective of macrophage presence, after prolonged in vitro culture.
• The findings clarify the role of ECs in immune surveillance and T cell activation.