Cytokine profiling by multiplex immunoassay as a valuable tool for diagnosis and monitoring patients with autoinflammatory disorders

Background Autoinflammatory diseases (AIDs) comprise a heterogeneous group of immune disorders with poor genotype-phenotype correlation. AIDs are characterised by recurrent or chronic inflammation, secondary to antigen-independent activation of the immune system, causing increased pro- inflammatory cytokines. Discriminating AID from other diseases with overlapping clinical and biochemical abnormalities remains challenging. Multiplex immunoassays (MIA) can quantify cytokines in a variety of biological fluids. MIA are faced with diagnostic challenges, such as lack of standardization and reference values, availability, and limited datasets based on single centre experiences. Methods In our centre, we perform MIA (Luminex) in pediatric and adult patients with persistent or recurrent inflammation. Additional to systemic cytokine profile, clinical experts allocated patients using routine investigations to different diagnostic categories (AID, autoimmune disease (AI), infection, hemophagocytic lymphohistiocytosis (HLH) or macrophage activation syndrome (MAS). Results We present the results of a 6-plex panel of serum cytokines (IL-1b/IL-1Ra/IL-6/IL-18/CXCL9/TNFa) in patients (n=50;age 4m-65y) and healthy controls. Significant differences between diseases can be noted. Increased IL-18 and IL-18/CXCL9 ratio is present in AID and MAS patients. Furthermore, monitoring disease activity is possible, with higher IL-1(Ra) and IL-6 present in active AID compared to inactive disease. Conclusions We provide proof-of-concept for a 6-plex cytokine panel useable in early detection and monitoring of AIDs. With a multicentre research initiative in Flanders (FEBRIS), we aim to optimize and validate these preliminary findings in a prospective cohort of patients (n=1200) with AID suspicion. We believe this assay will enhance early diagnosis, monitoring, and personalized treatment of AID patients with improved outcome.