Objective:

The study aimed to measure the number of two specific types of immune cells, lymphocytes and eosinophils, in the lining of the duodenum (part of the small intestine) and the rectum of horses with asthma.

Animals Involved:

There were 18 horses in total:

• 8 healthy horses (control group)
• 10 horses with asthma

Procedures:

• Status of Asthmatic Horses: The asthmatic horses were studied in two different states:
  1. Symptomatic: After the horses had been exposed to moldy hay for 6 weeks.
  2. Asymptomatic: Either 3 or 7 months after being fed alfalfa pellets (4 of the horses) or treated with an inhaled drug called fluticasone (6 of the horses).
• Biopsies: Samples of the lining of the duodenum and rectum were taken from each horse using an endoscope.
• Cell Counting: The eosinophils were counted on slides that were specially stained. Techniques called immunohistochemistry were used to identify T lymphocytes (using CD3) and B lymphocytes (using CD20).

Results:

• The lining of the duodenum and rectum in both asthmatic and healthy horses only contained T lymphocytes (CD3).
• When compared to healthy horses, the asthmatic horses showing symptoms had significantly more T lymphocytes in the lining of the duodenum and the tissue layer underneath it.
• Among the asthmatic horses, those treated with fluticasone had fewer T lymphocytes in the lining of the rectum compared to those showing symptoms.

Clinical Relevance:

• The findings suggest that asthmatic horses have more T lymphocytes in the lining of the duodenum and rectum. This increased number suggests inflammation, which might be caused by a general inflammatory response in the body or a local reaction to hay allergens the horses ate.
• The study doesn’t specify whether the inflammation is due to a widespread (systemic) effect or just a localized one, as broader markers of inflammation weren’t studied.

In simpler terms, the study found that asthmatic horses have more inflammation-indicating cells in certain parts of their intestines, especially when they show asthma symptoms. This might be due to their body’s overall inflammation or a reaction to allergens in the hay they consume.