Effect of lidocaine on the function of immunocompetent cells. II. Chronic in vivo exposure and its effects on mouse lymphocyte activation and expression of immunity.

In vivo exposure of mice to lidocaine (0.25 mg/10 g body weight 4 times a day for 7 days) resulted in impairment of immunocompetent cell function. Spleen lymphocytes removed from animals immediately and 3 days after lidocaine exposure showed changes in their surface charge properties, inhibition of blastogenesis in response to concanavalin A and lipopolysaccharide, and inhibition of antigen-stimulated activation as measured by the mixed lymphocyte reaction. Lymphocytes from animals sensitized to keyhole limpet hemocyanin showed a significantly lower capacity to produce macrophage migration inhibitory factor 8 days after termination of exposure to lidocaine. Animals exposed to the drug were unable to accumulate an adequate number of immunocompetent cells at the site of challenge with a foreign substance (i.e. dextran), and the ability of the animals to destroy tumor cells nonspecifically and specifically was also impaired. The results indicated that chronic exposure to lidocaine resulted in impairment of lymphocyte function, even in the subsequent absence of the drug, and in significant changes in the expression of the immune response.