The effect of lidocaine on in vitro adhesion and migration of equine neutrophils

The effect of lidocaine on in vitro migration and adhesion of equine neutrophils was evaluated. Neutrophils were isolated from equine whole blood using a Percoll-gradient centrifugation protocol. Purified neutrophils were incubated with lidocaine at concentrations from 0.1 to 1000 μg/ml for 30 min at 37 °C, after calcein loading. Neutrophil integrin-mediated adhesion in response to stimulation with 100 nM LTB4, 100 nM PAF, or 100 ng/ml IL-8, or integrin-mediated migration in response to stimulation with 100 nM LTB4, 150 nM PAF, or 100 ng/ml IL-8 was assessed. Statistical significance was set at P < 0.05. Neutrophil adhesion was significantly increased in response to all three stimulants. IL-8-stimulated adhesion was significantly increased when neutrophils were incubated with 1 mg/ml lidocaine, compared to lower lidocaine concentrations. LTB4-stimulated adhesion was significantly increased when neutrophils were incubated with 1 mg/ml lidocaine compared to that at 5 μg/ml lidocaine. Migration was significantly increased in response to IL-8. IL-8 and LTB4 stimulated migration was significantly increased when neutrophils were incubated with 1 mg/ml lidocaine, compared to lower lidocaine concentrations. In conclusion, lidocaine did not inhibit neutrophil migration or adhesion in vitro at therapeutic concentrations, and increased migration and adhesion at higher concentrations.