W102 - Multi-parametric Interrogation for Systemic Immunological Perturbations in Patients with Juvenile Idiopathic Arthritis After MRNA Vaccination

Abstract Text: Juvenile Idiopathic Arthritis (JIA) is a T-cell-driven auto-immune disease affecting joints. In the Coronavirus Disease of 2019 (COVID-19) pandemic, mRNA vaccines elicit a robust immune response in healthy adolescents and young adults. There is an unmet need to determine if the COVID-19 mRNA vaccine has a systemic effect in children with JIA.

We employed a high-dimensional approach, interrogating the peripheral blood mononuclear cells (PBMC) of 33 patients with JIA using a 43 markers mass cytometry panel. Quality check, batch-effect correction, flow-cytometry clustering by Self-Organising Maps, annotation and visualisation after t-distributed stochastic neighbour embedding dimensional reduction were done. Absolute differences in cell frequencies were expressed as mean differences with 95% confidence intervals (CI).

Overall, there were no observable differences in the expression patterns of cytokines, checkpoint inhibitors, and inducible co-receptors with no significant changes in 42 immune subset frequencies across the immunomes at pre-vaccination, post-first dose, and post-second dose (ANOVA with Bonferroni correction). Specifically, the immune cell subsets that produced inflammatory cytokines (TNFα, IFNɣ, IL-2, IL-6, IL17A) had no significant mean frequency changes at post-dose 1 and 2 compared to pre-vaccination. The T regulatory cell frequencies showed no change at post-dose 1 (mean difference: -0.138 (95% CI: -0.636 to 0.360)%) and post-dose 2 (mean difference: -0.003 (95% CI: -0.458 to 0.452)%).

Our results indicate the specificity of the mRNA vaccine in eliciting a controlled antigen-specific response without generalised immunological changes.