Gustavo Elena

Effects of sevoflurane general anesthesia: immunological studies in mice.

Based on the immunomodulatory effects of anesthesia and surgery, a study was undertaken to assess the effect of sevoflurane anesthesia on the immune system in a murine model without surgery. Adult male mice were anesthetized with 3% sevoflurane (1.2 minimal alveolar concentration, MAC) in oxygen for 40 min, whereas nontreated animals served as controls. After sevoflurane anesthesia, peripheral blood leukocyte counts, the splenic composition and in vitro macrophage phagocytic activity and lymphoproliferative response were assessed. The in vivo specific immune response to sheep red blood cells (SRBC), a conventional T-dependent antigen was determined. In addition, liver, spleen, thymus and kidney histopathology and also hepatic and renal functions after anesthesia were studied. Sevoflurane diminished the number of peripheral blood lymphocytes and splenic B-cell counts, enhancing CD4+ lymphocytes in spleen. The in vitro functionality of macrophages and the mitogen-induced lymphoproliferative response were preserved, while the in vivo immune response to SRBC was enhanced in treated animals. Microscopic studies revealed conserved architecture of the spleen, thymus, lymph node, liver and kidney, and there were no differences in serum parameters of hepatic and renal functions between treated and control groups. Our results suggest that 3 days after the anesthetic exposure, animals treated with sevoflurane modulated their peripheral blood leukocyte counts, splenic lymphoid composition and the characteristics of the specific response to SRBC, while there was no evidence of hepatic or renal toxicity.

Effects of repetitive sevoflurane anaesthesia on immune response, select biochemical parameters and organ histology in mice

Animal and technical models often require repeated anaesthetic administrations for surgical procedures. As there is evidence for immunomodulatory effects of anaesthesia, the effects of repeated exposure to sevoflurane anaesthesia on the immune response in mice were studied. Sevoflurane was administered in vivo under conditions that simulate those in clinical procedures. Adult male mice were anaesthetized with 3% sevoflurane in oxygen for 40 min weekly for 3 weeks. Untreated animals served as controls. After sevoflurane anaesthesia, peripheral blood leukocyte counts, the composition and in vitro function of spleen cells (lymphocytes and macrophages) and the in vivo immune response to a conventional T-dependent antigen were assessed. In addition, liver, spleen and kidney histopathology and also hepatic and renal function were studied. Three days after the latest anaesthetic procedure, the absolute number of both leukocyte and lymphocyte counts were reduced in peripheral blood. Splenic cell composition (LB, LTCD3+, LTCD4+ and LTCD8+), macrophage function and the mitogen-induced lymphoprolipherative response were preserved. Yet, the in vivo humoral response to a conventional antigen was augmented following the antigenic challenge. Assessment at day 9 after the last anaesthetic procedure revealed the persistence of the humoral response alteration. Nevertheless, sevoflurane-treated animals showed no evidence of histological changes or alteration in hepatic or renal function.

Inhalatory anesthetic (HALOTHANE) associated changes in the immune response in mice

The extent of surgery, the patients age, health status and other factors may contribute to alteration of the immune system during anesthesia and surgery. In addition, inhalatory anesthetics may cause acute and chronic toxicity because of the production of intermediate and end metabolic compounds. The present work was undertaken to evaluate, both in vivo and in vitro, if repeated doses of halothane were able to affect the immune response in a murine model developed at our laboratory. Weekly doses of halothane were administered to mice subjected to no surgery and three days after the last anesthetic-exposure, several immunologic parameters were assessed. Results on the in vivo response to sheep red blood cells showed that halothane treatment increased the amount of specific antibody secreting B-cells, without affecting the delayed type hypersensitivity reaction to the same antigen. In vitro studies on spleen cell composition showed that halothane re-exposure diminished the number of CD4+, CD8+ and B-cells. Such changes were not translated into alterations on the mitogen-driven lymphoproliferation, as well as macrophage phagocytic and lytic functions. Our results indicate that halothane re-exposure is able to modulate the immune response affecting both the number of antibody secreting cells involved in a specific in vivo response, and the splenic lymphoid cell composition. Since such halothane-induced immune alterations might bias the results of a wide range of physiological research, even those involving other systems, a careful selection of the anesthetic agent and methods by which the compound is administered is advisable.

Halothane–associated enhancement of the secondary immune response to sheep erythrocytes in mice: cell transfer studies

The effect of halothane anesthesia on the humoral immune response to sheep red blood cells was studied in mice immunized twice, with a 15–day interval. On both occasions, mice were exposed to 1.5% halothane for 40 min immediately after sensitization. Halothane reexposure resulted in increased numbers of IgG–secreting cells (IgG–SC) as well as circulating 7S–serum agglutinins. To examine further whether this effect could be obtained in syngeneic recipients, adoptive transfer experiments employing spleen cells were performed. While mice receiving cells from unimmunized and anesthetized donors displayed significantly higher levels of IgG–SC, recipients of cells from normal, immunized and immunized–anesthetized donors showed a depressed response when compared to control counterparts. Besides the possibility of an enhancing effect of halothane reexposure on the humoral response, this procedure may counteract normal physiological immunoregulatory processes during the generation of the immune response.

Effects of halothane reexposure in female mice and their offspring.

Female CBi mice subjected to multiple exposures to halothane inhalation anesthesia before mating were investigated for the potential effects of such intervention on a specific antibody response mounted by them and their offspring. An assessment of the toxicologic and reproductive performance of female mice undergoing anesthesia was also performed. Adult female mice received three episodes of halothane anesthesia at weekly intervals. Seventy-two hours after the last dose, mice were subjected to the following procedures: 1) study of the specific humoral immune response to sheep red blood cells (SRBC); 2) hematologic, hepatologic, and histopathologic studies; and 3) mating with syngeneic sires. Halothane-treated females had increased amounts of specific antibody secreting B cells, with liver studies showing evidence of microscopic fatty changes and decreased lipid peroxidation. Anesthesia did not alter reproductive performance but lowered offspring survival. Offspring displayed depressed antibody response after challenge with SRBC at weaning and at 60 d of age. The anti-SRBC antibody response that was found to be enhanced in halothane anesthetized females, seemed to be conversely impaired when studied in the offspring.

Oxygen tension-associated changes on secondary immune response in halothane or isoflurane anesthetized mice.

The impact that reexposure to anesthetics delivered in 100% oxygen or in synthetic air (21% oxygen/79% nitrogen) has on the secondary humoral immune response to sheep red blood cells was studied. Mice were immunized twice with a 15‐day interval and anesthetized immediately after each antigenic challenge with 1.5% halothane or 1.5% isoflurane for 40 min. Halothane in oxygen resulted in increased numbers of IgG‐secreting cells (IgG‐SC), while halothane in air depressed the response when compared to control mice. In contrast, isoflurane vaporized in oxygen did not affect IgG‐SC numbers, while isoflurane given in air lowered the response. Furthermore, neither 100% oxygen, nor the stress of being in an anesthesia chamber breathing synthetic air for 40 min had any immunological effect in non‐anesthetized mice.

Halothane anesthesia in mice: effect on the phagocytic activity and respiratory burst of peritoneal macrophages.

Objective: To study the effects of halothane anesthesia in mice not undergoing surgery on elements of the inflammatory and stress response; this involved assessment of the phagocytic activity and respiratory burst of peritoneal macrophages as well as plasma corticosterone levels and peripheral leukocyte counts. Methods: There were 2 experimental groups, i.e. mice anesthetized with halothane 1.5% in oxygen for 40 min and a control group of mice subjected to the same manipulations but no anesthesia. At the end of the anesthetic or sham procedure, peritoneal macrophages were evaluated for phagocytic and lytic activity after an immune challenge and spontaneous respiratory burst (chemoluminiscence). Plasma corticosterone and leukocyte counts in peripheral blood were evaluated as indicators of the stress response. Results: In halothane-anesthetized mice, increased numbers and activity of phagocytic cells were found, with regard to the number of ingested and digested particles, compared to the nonanesthetized group. The ex vivo peritoneal macrophage respiratory burst without antigenic stimulation also showed a higher response in anesthetized mice compared with the nonanesthetized controls. Halothane administration did not alter corticosterone levels. Treated and control mice displayed similar leukocyte profiles in peripheral blood, except for lower lymphocyte counts in the controls compared to the halothane group. Typical correlation between corticosterone and leukocyte subsets, together with a high positive correlation between plasma corticosterone and phagocytic cell counts, were found only in the control group. Conclusion: Halothane anesthesia might have beneficial effects on the inflammatory response mediated by phagocytes, namely the activity and efficiency of peritoneal macrophages, in a setting where plasma corticosterone and peripheral leukocyte counts were not affected.