Blood samples taken under anaesthesia can be used as a source of non-diseased controls for immune-based assays.

This study includes only the whole blood (bulk) RNAseq data from tempus tubes described below; a full abstract for the overall study is provided. Recruiting very young, healthy children to serve as age-matched controls in research settings presents substantial ethical and practical challenges. One potential approach to address this issue is to recruit healthy children who are referred for elective procedures under general anaesthesia. However, infants are typically anaesthetised using volatile anaesthetics before a cannula is inserted to administer additional drugs. Consequently, blood samples are accessible after the onset of a drug-induced coma. As prolonged exposure to inhaled anaesthetic agents is known to have immediate immune modulatory effects which could bias any comparisons between samples taken while awake and under general anaesthesia, we set out to investigate whether immune changes could be observed in samples collected immediately after gas induction in children undergoing elective dental procedures. The composition and transcriptional profile of whole blood immune cells were evaluated by multiparameter flow cytometry and bulk RNA-sequencing, respectively. Cryopreserved PBMCs were used to study changes in the phenotype of activated CD4+ T cells by single-cell RNA-sequencing analysis using the 10x genomics platform. We report that inhaled anaesthetic induction using a combination of nitrous oxide and sevoflurane has minimal effect on the immune system composition and transcriptional profile and does not alter the phenotype of activated CD4+ T cells stimulated with Staphylococcal Enterotoxin B (SEB). However, we did observe changes in absolute cell counts. Therefore, blood samples collected during elective procedures under general anesthesia may offer a valuable opportunity for recruiting healthy children for research studies, depending on the planned tests. This study recruited a total of ten individuals referred for elective dental procedures under general anaesthesia between three and six years of age. On the day of the procedure, prilocaine cream was applied for at least 15 minutes on both antecubital fossae to facilitate the insertion of a 22G cannula in the cephalic or medial cubital veins. Analgesic cryogenic ethyl chloride spray was used after skin preparation and ultrasound guidance employed if the vein could not be seen or felt. A first blood sample was taken before any administration of anaesthetic gases (pre-SEVO). Parents were asked to confirm consent for an inhalational induction at that point. A mix of nitrous oxide and oxygen was then used, increasing progressively the concentration of sevoflurane to 8%. Once the child was asleep, the nitrous oxide was turned off and a second blood sample was taken via the cannula (post-SEVO) *************************************************************** Raw files for human/patient samples were not submitted to GEO due to concerns about submitting personally identifiable sequence data for open access. ***************************************************************