Established and emerging immune signatures in paediatric inflammatory disease: Insights from plasma proteomics

Inflammatory diseases can look clinically similar while reflecting distinct underlying immune biology. Fever, rash, elevated inflammatory markers, vascular involvement, and organ dysfunction may occur across autoimmune disease, autoinflammatory disease, viral infection, and cytokine storm syndromes. For researchers, this creates a central challenge: how can biologically meaningful immune signatures be distinguished from broad systemic inflammation?

This question is especially relevant in paediatric research. Children are not simply smaller adults; immune development changes over time, and sample collection can be difficult when working with young or acutely ill patients. In the recent webinar “Immune Profiling of Inflammatory Diseases in the Paediatric Population,” Dr. Pui Lee, physician-scientist at Boston Children’s Hospital and Associate Professor of Pediatrics at Harvard Medical School, discussed how plasma cytokine profiling can help explore inflammatory disease biology from very small sample volumes.

Drawing from the webinar, this post highlights selected established and emerging immune signatures in Kawasaki disease, viral infection, MIS-C, systemic juvenile idiopathic arthritis, and macrophage activation syndrome and explores how plasma proteomics can support immune profiling in limited, highly precious paediatric samples.

Why immune profiling is challenging in inflammatory disease

Cytokines and chemokines are central mediators of inflammatory disease, but they can be difficult to measure and interpret. Many are present at low circulating concentrations, some are more readily detected through downstream surrogate markers, and inflammatory signals may overlap across disease groups.

Dr. Lee also discussed practical assay challenges in autoimmune and inflammatory samples. Autoantibodies, rheumatoid factors, sample handling, anticoagulant choice, treatment effects, and biospecimen type can all influence cytokine readouts. This makes study design and biological context critical when interpreting proteomic data.

In paediatric studies, these challenges are compounded by sample volume limitations. Dr. Lee described limited blood volume as a major barrier in paediatric research and noted that low-volume approaches are particularly valuable when working with scarce clinical samples.

Established immune pathways: IL-18, CXCL9, and interferon-gamma biology

A useful immune profiling approach should recover known biology as well as reveal unexpected patterns. In the webinar, Dr. Lee described IL-18 and CXCL9 as examples of expected pathway-level signals.

IL-18 was elevated in systemic juvenile idiopathic arthritis and macrophage activation syndrome, consistent with known inflammatory biology in these conditions. CXCL9, a chemokine induced by interferon-gamma, was used as a surrogate marker of interferon-gamma activation, a pathway associated with macrophage activation syndrome and MIS-C.

This type of pathway-level confirmation matters because immune biomarkers rarely act in isolation. As discussed in the webinar Q&A, interpreting multiple analytes within the same pathway, supported by replication cohorts, can strengthen confidence that a measured signal reflects meaningful biology rather than noise.

Emerging immune signatures: IL-17 in Kawasaki disease and EBV-associated activation

Beyond expected inflammatory pathways, the webinar highlighted emerging signatures with potential value for biomarker research.

In Kawasaki disease, Dr. Lee’s team observed a distinctive IL-17-associated pattern. IL-17A, IL-17C, and IL-17F were elevated in Kawasaki disease compared with several other paediatric inflammatory and febrile disease groups. IL-17A and IL-17F were also higher in patients with coronary artery aneurysm in the cohorts discussed, suggesting that these proteins may reflect disease-associated biology or identify subsets within clinically defined Kawasaki disease.

The webinar also explored viral infection, with EBV emerging as a particularly informative example. Compared with other viral infections, EBV was associated with elevated interferon-gamma-related chemokines and cytokines, including CXCL9, CXCL10, CXCL11, IL-18, and IL-27. Dr. Lee also described expansion of CD38-positive, HLA-DR-positive T cells in EBV infection, overlapping with cellular signatures seen in cytokine storm syndromes.

Together, these findings illustrate how plasma proteomics can help researchers compare immune pathway activation across diseases that may share inflammatory features but differ in underlying biology.

A proteomics approach for limited, precious inflammatory disease samples

Olink PEA technology uses pairs of oligonucleotide-labeled antibodies that bind to the same target protein. When the antibodies bind in proximity, their DNA tags hybridize and are extended, generating a DNA reporter that can be quantified by qPCR or next-generation sequencing. In the webinar, Dr. Lee described how this dual-recognition approach supports sensitive and specific measurement of cytokines and chemokines from minimal sample volume.

For inflammatory disease research, this combination of high multiplexing, sensitivity, and low sample input can help researchers profile immune mediators across limited biospecimens, longitudinal cohorts, and complex comparator groups. It can also support the transition from broad immune discovery toward more focused biomarker translational analysis.

As Dr. Lee emphasized, these findings are research observations. They should not be interpreted as diagnostic claims or treatment recommendations. Rather, they demonstrate how plasma proteomics can help identify immune signatures, generate biomarker hypotheses, and clarify pathway-level biology in complex inflammatory disease research.