Pulmonary metastases, a potential biologic consequence of anesthetic-induced immunosuppression by thiopental

This set of experiments was devised to determine the effects of the commonly employed anesthetic induction agent, thiopental, on the incidence of pulmonary metastases in a murine fibrosarcoma system. A correlation was made with cell-mediated immune responses in vivo and in vitro. In two separate experiments, thiopental-treated mice had a significantly increased incidence of pulmonary metastases. This was correlated with an impaired delayed hypersensitivity reaction to the de novo antigen. 2,4-dinitrochlorobenzene (DNCB) and a suppressed mixed leukocyte culture (MLC) reaction. However, if animals were sensitized with DNCB 5 days prior to receiving pentothal, no impairment of DNCB reactivity was noted. This suggests strongly that the observed defect is in the afferent arm of the immune response. Thiopental suppresses cell-mediated immune responses in this system, and the observed biologic consequence is an increase in pulmonary metastases.