Langerhans cells within the follicular epithelium and the intradermal sweat duct in equine insect hypersensitivity “Kasen”.

This study investigates the characteristics and behaviours of Langerhans cells, specific types of immune cells, within follicular epithelium and intradermal sweat duct in horses affected by “Kasen”, a type of equine insect hypersensitivity.

Research Methodology and Findings

The researchers utilized histopathologic and electron microscopic methods to observe Langerhans Cells (LCs) in horses affected by equine insect hypersensitivity, specifically “Kasen”.

They found that:

• Under light microscopy, LCs were mostly present within the follicular epithelium and intradermal sweat duct compared to the epidermal layer and normal skin.
• The formation of several aggregated foci, or clusters of cells, was occasionally observed.
• Electron microscopic examination showed LCs within the follicular epithelium and intradermal sweat duct extending their dendritic processes, or branches which form connections between cells, among the keratinocytes, which are cells involved in developing skin and hair.
• These LCs contained Birbeck granules, mitochondria, rough endoplasmic reticula, and ribosomes in the cytoplasm.
• They identified numerous Type 2 and Type 3 LCs within these regions. Type 2 LCs displayed endocytosis – the process of cells intaking substances – and a high number of Birbeck granules. Type 3 LCs contained multivesicular bodies and endosomes, which are used for transporting proteins, of various sizes in their structure.
• Inactive Type 1 LCs were rarely seen and when present, they featured a narrow and clear-looking cytoplasm.

Implication of findings

The study’s findings suggest that the Langerhans cells found within the follicular epithelium and intradermal sweat duct in the lesions caused by Kasen might play an important role in the immune response to this condition. The type and activities of the cells potentially express a specific stage during the immune response where they recognize, intake, and process antigens, which are harmful substances that trigger an immune response. This gives a better understanding of equine insect hypersensitivity at the cellular level, and it could help with developing better treatment strategies in the future.