Background aims: The effects of two anesthetic agents, alfentanil and isoflurane, on the macrophage-monocytic system and the relation with the adrenocortical-hypophyseal axis were analyzed.
Material and methods: Thirty ASA I-II patients submitted to elective surgery were distributed into two groups: group I, analgesic anesthesia with alfentanil 100 micrograms/kg, a perfusion of 2-3 micrograms/kg/min and naloxone 0.2-0.4 mg upon termination of surgery; group II, inhalation anesthesia with isoflurane at 2-2.5% and O2/air = 1/1. HLA-DR membrane receptors and vimentin threads of the cytoskeleton were determined in basal conditions, at one hour and two hours of induction and upon termination of surgery by means of indirect immunofluorescence with the use of monoclonal antibodies. Phagocytosis of latex particles was also measured and ACTH and cortisol levels were obtained by radioimmunoassay.
Results: In group I (alfentanil) a decrease (p < 0.01) of all the monocyte parameters analyzed, which was more significant than that observed in group II (isoflurane), was observed. In group II only the expression of HLA-DR and the index of phagocytosis (p < 0.05) were statistically significant. Following the administration of naloxone a reversion of these parameters was observed. The maximum immune depression corresponded with the lowest values of ACTH and cortisol (group I) with surgical stress being discarded as the cause of this immunodepression.
Conclusions: Alfentanil produces a monocytic depression which reverses following the administration of naloxone, thus discarding surgical stress as the cause of this immunodepression suggesting a mechanism mediated by opiate receptors. With regards to isoflurane, the functions of the mononuclear-phagocytic system were hardly altered in the patient studied.