Procoagulant activity in respiratory tract secretions from horses with chronic pulmonary disease.

The research paper studies the apparent procoagulant activity in the respiratory tract fluids of horses suffering from chronic pulmonary disease. Nearly 59% out of 103 samples showed significant procoagulant activity, especially from severely affected horses. The increase in procoagulant activity was associated with a higher quantity of neutrophils, a type of white blood cell, in the secretions.

Experiments and Findings

• The researchers collected respiratory secretions from horses with chronic pulmonary disease. These secretions were then broken down using centrifugation, and the cell-free supernatants (‘sol phases’) were examined.
• Out of the 103 samples of horse secretions tested, 61 showed procoagulant activity (PCA), representing 59% of the total. This activity was found most commonly in severely affected animals. Furthermore, PCA was directly related to the number of neutrophils (a type of white blood cell) found in the respiratory secretions.
• In around 70% (12 of 17) of tested secretions, the time it took for a clot to form decreased incrementally as more of the sol phase was introduced. This indicates a dose-dependent relationship between the quantity of sol phase and clotting time.
• However, in 4 secretion samples, increasing quantities of sol phase led to a partial reversal or inhibition of PCA, revealing some variables in the coagulation response.

Characterization of PCA

• The PCA was tentatively identified as tissue factor due to its stability at varying temperatures and its reaction to certain substances. It was observed to be inhibited by phospholipase C, an enzyme that breaks down phospholipids, and concanavalin A, a lectin (protein that binds to specific sugars) typically used in biological research.
• The researchers tested the PCA’s effect on human plasma with a deficiency in factor VIII, a clotting protein. They found that the PCA induced clotting in these samples, suggesting a possible function for PCA in coagulation.
• However, in all but one sample, PCA did not enhance clotting in human plasma deficient in another clotting protein, factor VII. This exception indicates that the role of PCA in clotting may not be fully understood yet.

Conclusion

• Overall, the study finds that procoagulant activity can serve as a reliable indicator of airway inflammation in horses with chronic pulmonary disease. This finding could potentially be used to aid in the diagnosis or monitoring of this disease in the future.