Assessment of leukotriene B4 production in leukocytes from horses with recurrent airway obstruction.

This research study aimed to measure the production of leukotrienes (LT), particularly leukotriene B4 (LTB4), in the leukocytes or white blood cells from horses with recurrent airway obstruction (RAO). The test was conducted on certain cells from both RAO-affected and healthy horses at different intervals after stabling. The study found that RAO-affected horses had increased LTB4 production, which may contribute to lung inflammation and neutrophil infiltration related to RAO.

Objectives and Methods

• The main objective of the research was to evaluate the biosynthesis of leukotriene (LT), a group of biologically active compounds produced by leukocytes, in peripheral blood neutrophils (PBNs) and bronchoalveolar lavage fluid (BALF) cells from horses with recurrent airway obstruction (RAO).
• The experiment included 6 horses with RAO and 6 healthy ones. Their health conditions were evaluated before and 6, 24, and 48 hours after stabling through clinical and mucus scores as well as the measurement of the maximal change in pleural pressure (deltaPpl max).
• The PBNs and BALF samples from each horse were isolated and examined. Additionally, the cells were provoked with a calcium ionophore in the presence of arachidonic acid, leading to the production of LTC4 and LTB4, two types of leukotrienes.
• The amount of LTC4 and LTB4 produced for every 1,000,000 cells was measured.

Findings

• The health condition of the RAO-affected horses, assessed through clinical and mucus scores and deltaPpl max, deteriorated during the stabling period, unlike the healthy ones.
• The production of LTB4 was higher than LTC4 in the neutrophils and BALF cells from both groups of horses.
• However, the production of LTB4 by the PBNs was lower in the RAO-affected horses than it was in the control group at all times.
• A significant increase in LTB4 production by BALF cells was observed in RAO-affected horses after 6 hours of stabling, which was concurrent with the migration of neutrophils into the airways. No such change was observed in the control horses during the stabling period.

Conclusion

• The study concludes that there is an increased production of LTB4 in the airways of horses suffering from RAO, compared to healthy horses.
• This increased presence of LTB4 potentially contributes to the infiltration of neutrophils into the lungs and the persistent inflammation associated with RAO.