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

Clara Domingo-Vila^1*Evangelia D Williams¹Megan E Smithmyer²Basilin Benson³Lauric Ferrat^4,5Sefina Arif¹Michelle Hudson⁴Becky Dobbs⁴Matthew Johnson⁴Iain Yardley⁶Cate Speake²Richard A Oram⁴Timothy Ian Martin Tree¹Benjamin Blaise^6,7,8

• ¹School of Immunology and Microbial Sciences, Faculty of Life Sciences & Medicine, King's College London, London, England, United Kingdom
• ²Center for Interventional Immunology, Benaroya Research Institute, Seattle, USA, Seattle, United States
• ³Center for Systems Immunology, Benaroya Research Institute, Seattle, USA, Seattle, United States
• ⁴Department of Clinical & Biomedical Sciences, University of Exeter Medical School, Exeter, United Kingdom, Exeter, United Kingdom
• ⁵Department of Genetic Medicine and Development, University of Geneva, Geneva, Geneva, Switzerland
• ⁶Guy's and St Thomas' NHS Foundation Trust, Evelina London Children's Hospital, Department of Paediatric Surgery, London, United Kingdom, London, United Kingdom
• ⁷King’s College London, Centre for the Developing Brain, St Thomas’ Hospital, London, United Kingdom, London, United Kingdom
• ⁸Guy's and St Thomas' NHS Foundation Trust, Evelina London Children's Hospital, Paediatric Anaesthetic Department, London, United Kingdom, London, United Kingdom

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. As infants are typically anaesthetised using volatile anaesthetics before a cannula is inserted to administer additional drugs, blood samples are easily accessible after the onset of a drug-induced coma. However, since prolonged exposure to inhaled anesthetic agents is known to have immunemodulating effects that could impact their suitability as experimental controls, we aimed to investigate whether immune changes are also 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 polyclonally 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 observed an increase in absolute cell counts in specific leucocyte populations. We conclude that 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.Members of the EXE-T1D consortium: