Culicoides antigen extract stimulates equine blood mononuclear (BMN) cell proliferation and the release of eosinophil adherence-inducing factor(s).

The study investigated how the injection of a Culicoides antigen extract prompts T lymphocyte and eosinophil accumulation in the skin of horses, contributing to the condition known as sweet itch. It also discovered a connection between these blood cells’ proliferation and the release of certain factors that induce eosinophil adherence, which could affect its function in diseased horses’ skin.

Key Research Findings

• Researchers used a Culicoides antigen extract (CAgX) in the study, which upon intradermal injection, triggered an accumulation of T lymphocytes and eosinophils in the skin of horses diagnosed with sweet itch, a common equine skin disease.
• It was observed that blood mononuclear cells (BMN) from normal horses when stimulated by mitogens such as PHA or antigens like Tetanus Toxoid (TT), proliferated and released specific soluble factors that are capable of inducing eosinophil adherence.
• CAgX led to a concentration-dependent proliferation of the BMN cells, observed both in horses with sweet itch and healthy horses. The stimulation index was documented as 29 (13) for diseased horses and 17 (7) for healthy ones during the active disease phase.
• The study also demonstrated the release of a heat-labile factor that caused eosinophil adherence. Sweet itch affected horses presented with 6.0 (1.6) per cent adherence against 1.3 (0.4) per cent; while healthy horses demonstrated 6.6 (0.5) per cent adherence against 0.9 (0.1) per cent for supernatants from CAgX stimulated and non-stimulated BMN cells, respectively.

Notable Implications

• The research implied that certain soluble proteins released from T lymphocytes could potentially influence the functioning of eosinophils in the skin lesions of sweet itch affected horses, thus providing insights into the pathogenesis of the condition.
• This study presents potential markers for the disease’s progression and also provides a scientific base for developing novel therapeutic approaches targeting eosinophils and T lymphocytes interaction within sweet itch lesions.