Role of the eosinophil in serum-mediated adherence of equine leukocytes to infective larvae of Strongylus vulgaris.

This study investigates the interaction between horse immune cells (leukocytes) and Strongylus vulgaris larvae, specifically focusing on the role of an immune cell type known as the eosinophil. The goal is to better understand the immune response to this equine parasite.

Examination of Interaction Between Leukocytes and S. vulgaris Larvae

• The researchers examined how equine leukocytes interact with larvae of S. vulgaris in the presence of normal and immune horse serum (blood fluid).
• They found that immune serum increased the adherence of certain immune cells found in the buffy coat (the layer of white blood cells and platelets that form in a sample of blood when centrifuged) from horses with a high number of eosinophils (a type of white blood cell often increased in response to an allergic reaction or infection) due to S. vulgaris infection.
• The main cells that stuck to the S. vulgaris larvae were the eosinophils.

Role of Eosinophils, Neutrophils, and Mononuclear Cells

• Further studies using immune cell populations rich in eosinophils, neutrophils and mononuclear cells confirmed that eosinophils were the primary cell type adhering to the larvae and immobilizing them.
• Neutrophils were less adherent and did not immobilize the larvae, and mononuclear cells did not stick at all.
• A lack of immobilization by normal eosinophils from ponies without infection suggests that an in vivo (in the body) activation of eosinophils takes place in infected animals.

Use of Immune Serum and Its Implications

• The ability of immune serum to promote adherence of cells was less effective when presented with Strongylus edentatus or mixed species of Cyathostominae, which suggests that this response is species-specific.
• Normal serum (from uninfected horses) promoted less cell adherence than immune serum.
• The adherence promoted by normal serum was removed with heat inactivation, indicating the role of a complement-mediated reaction; this is an immune system process that helps or “complements” the ability of antibodies to clear pathogens.

Role of Immune Globulins (Antibodies)

• Globulins (a family of proteins that includes antibodies), absorbed on pieces of S. vulgaris worms, didn’t enhance adherence, suggesting there are shared antigens (substances triggering immune response) between larvae and adult stages. These shared antigens seem to play a crucial role in promoting the adherence of eosinophils.

Overall, this research provides insight into the specific mechanisms by which the immune system of horses responds to the S. vulgaris parasite, which could potentially be useful for the development of new treatments or preventative measures.