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 microg/ml for 30 min at 37 degrees C, after calcein loading. Neutrophil integrin-mediated adhesion in response to stimulation with 100 nM LTB(4), 100 nM PAF, or 100 ng/ml IL-8, or integrin-mediated migration in response to stimulation with 100 nM LTB(4), 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 1mg/ml lidocaine, compared to lower lidocaine concentrations. LTB(4)-stimulated adhesion was significantly increased when neutrophils were incubated with 1mg/ml lidocaine compared to that at 5 microg/ml lidocaine. Migration was significantly increased in response to IL-8. IL-8 and LTB(4) stimulated migration was significantly increased when neutrophils were incubated with 1mg/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.