Abstract Introduction: The local salivary immunoglobulin A (IgA) is the predominant immunoglobulin in the saliva and plays an important role in the local immune defence system. It is believed that an abnormal production of IgA can cause systemic inflammatory diseases such as IgA vasculitis and IgA nephropathy. First and foremost, IgA vasculitis is the most common form of childhood vasculitis which is characterized by a skin rash and a classical triad of symptoms involving the gastrointestinal system, musculoskeletal and renal system which is not always present. The incidence of IgA related disease is increasing across the world and it is a leading cause of chronic kidney disease. It should be noted that previous literature has demonstrated that poor oral hygiene may trigger IgA production and some studies have shown that children affected by IgA vasculitis are highly likely to suffer from dental caries pulp infection / inflammation, periapical infections and periodontal disease. Aim: The aim of the project is to determine whether children with IgAV have an increased production of salivary IgA by exploring the existing literature, piloting saliva collection methods, and validating the analytic performance of an assay to quantify salivary IgA as a potential biomarker for IgA induced vasculitis. Methods: This study was cross-sectional pilot study. Children were recruited from Alder Hey Children's NHS Foundation Trust Hospital. The target populations were three groups of children, the first group of children were those with a diagnosis of immunoglobulin A vasculitis (IgAV) who attended Alder Hey Children's NHS Foundation Trust Hospital for renal monitoring. The second group of children were termed a dental control group which was children who were attending the clinic at the paediatric dental department, Alder Hey Children’s Hospital. The third group of children were classed as a healthy control cohort. Patients were recruited as part of the IgA vasculitis (IgAV) study during their routine clinical follow up visitsfor regular kidney check-ups. A data collection sheet were used to collect data regarding the disease activity and oral health status using specific dental scoring tools. The Child Oral Health Impact Profile (COHIP) Questionnaire were completed and used in this study. The saliva samples were collected by either salivabio passive drool method or forced method. Saliva samples were centrifuged for 10 minutes at 800 g to remove any cells or debris and then the sample was isolated, stored and frozen at -80 degrees Celsius in 200 microL aliquots. Finally, IgA immunoglobulin was extracted and 7 quantified using Enzyme Linked Immunosorbent Assay (ELISA) assays. Initially healthy adult control samples were used to optimize the experiments. The study had full ethical approval. Results: A total of 15 children were recruited in this study. Of these, 5 patients had a diagnosis of IgAV, 5 children had a diagnosis of dental and oral issues, and the remaining 5 children were recruited as healthy controls. From this cohort, 10 (66.67%) of them were males and 5 (33.33%) were females. The median age of the first group which is the healthy cohort was 7 years, for the second group which is the IgAV the median was 8 years and for the third cohort which was patient with oral and dental caries the median age was 11 years. In the first group, the healthy control, the youngest participant was five years old and the eldest was eleven. In the IgAV cohort, the youngest child was six years old and the eldest was twelve. In the third group, which consisted of patients with oral and dental issues, the youngest participant was 8 years old and the eldest was 12 years old. The age range of the 15 children was 7 years. The concentration values of 108.1075, 55.2175, and 75.49 were recorded for the dental group, healthy group, and IgAV group, respectively. There was no significant differences were observed between the three groups. Furthermore, there was no statistically significant difference in the levels of IgA between the forced and passive samples which was taken from adult control to optimise the different methods to collect saliva. Regarding the Child Oral Health Impact Profile Questionnaire (COHIP) given to adult controls, three participants found it very good (37.5%), while one thought it was fair (12.5%). In terms of overall rating, three participants rated it very good, while one rated it poor. To make it easier for children, we provided a Modified Oral Health Questionnaire for the dental group. Out of five participants, two rated their dental health as 7, one as 9, one as 8, and one as 5. Overall, the questionnaire received an average rating of 7.2 out of 10, which is generally considered good based on the collected responses. Conclusion: This pilot study was not able to demonstrate any difference in the IgA concentrations in children with IgAV compared to children who had oral and dental concerns or healthy controls. Several factors could contribute to this outcome, that include the study limitations such as the small sample sizes. Further studies are required to explore the role of salivary IgA in this inflammatory disease.