Isolation and characterisation of equine dendritic cells

Area of Science:

• Equine Immunology
• Cell Biology
• Immunochemistry

Background:

• Dendritic cells are crucial for initiating T-cell responses in many species but remain understudied in horses.
• Understanding equine dendritic cells is vital for advancing equine immunology and developing effective immunotherapies.

Purpose of the Study:

• To develop a method for isolating blood dendritic cells in horses.
• To characterize the immunophenotype of equine blood dendritic cells.
• To assess the functional capacity of isolated equine dendritic cells in stimulating mixed leukocyte reactions (MLRs).

Main Methods:

• Adapted a method using adherence and metrizamide gradients for equine blood dendritic cell isolation.
• Utilized monoclonal antibodies (mAbs) for immunochemical analysis of isolated cells and tissues (lymph node, spleen).
• Employed flow cytometry to enumerate contaminating cells and compared immunochemistry data with cell morphology.

Main Results:

• Isolated equine blood cells showed typical dendritic cell morphology, with 62% positive for MHC Class II and low non-specific esterase activity.
• These cells expressed MHC Class I, LFA-1, EqWC1, EqWC2, and potentially bovine CD1b cross-reactive markers.
• Dendritic cell-enriched isolates were potent stimulators of MLRs, more so than peripheral blood mononuclear cells or adherent cells.

Conclusions:

• Equine dendritic cells isolated from blood express high levels of MHC Class I and II and LFA-1.
• These cells effectively stimulate a vigorous MLR, confirming their role in initiating T-cell responses.
• The expression of equine macrophage marker CZ2.2 suggests a close relationship between equine dendritic cells and mononuclear phagocytes.