Actions of non-steroidal anti-inflammatory drugs on equine leucocyte movement in vitro.

The research investigated the effects of four different non-steroidal anti-inflammatory drugs (NSAIDs) on the movement of equine leukocytes (white blood cells), using two different in vitro (outside a living organism) tests. The results showed that all four drugs can inhibit the movement of these cells in concentration-dependent manners, which could have implications for their use in equine medicine.

Research Methodology

• The researchers employed two different in vitro assays. The first one, called the Boyden chamber microfilter technique, is used to measure both chemokinetic (random cell movement) and chemotactic (movement directed by certain chemicals) locomotion. The second one, the agarose microdroplet assay, measures only chemokinesis.
• Two chemoattractants—zymosan-activated plasma (ZAP) and N-formyl-methionyl-leucyl-phenylalanine (FMLP)—were used. ZAP is used to attract polymorphonuclear (PMN) leucocytes, a type of white blood cell most commonly consisting of neutrophils, while FMLP is used to attract mononuclear (MN) leucocytes, which include lymphocytes and monocytes.
• The study examined the effects of six concentrations of each NSAID. The NSAIDs tested were indomethacin, phenylbutazone, oxyphenbutazone (a metabolite of phenylbutazone), and flunixin.

Results

• All four NSAIDs showed inhibitory effects on induced movement of both PMN and MN leucocytes in the Boyden chamber assay. This means they prevent or limit the movement of these cells when attracted by the chemoattractants.
• Oxyphenbutazone affected PMN cells only at the highest concentration tested, exhibiting a less potent effect compared to the other NSAIDs.
• In the agarose microdroplet assay, indomethacin, flunixin, and oxyphenbutazone inhibited both PMN and MN cell locomotion. Additionally, phenylbutazone suppressed the movement of PMN cells.
• Among the NSAIDs studied, flunixin was found to have the most potent effect in both assay systems.

Implications and Conclusions

• The findings may be significant for the usage of these NSAIDs in equine medicine. Both phenylbutazone and flunixin are commonly used in the treatment of equine pain and inflammation, and their effects on leukocyte movement can influence their therapeutic effectiveness.
• As the concentration levels used in the study are similar to those found in equine plasma and inflammatory exudates, the results could influence the dosage and application of these drugs in a real-world veterinary context.