A novel dominant-negative variant of IRF8 in a mother and son: Clinical, phenotypic and biological characteristics
Journal of Allergy and Clinical Immunology, 2025
Ham H., Isham C., Ristagno E., Correia C., Ennis S., Kandasamy R., Garapati K., Zhang C., Kohlhagen M., Sadighi Akha E., Rodriguez-Quevedo M., Schultz D., Chen B., Boyce T., Gregory S., Kohorst M., Dasari S., Murray D., Halling K., Kipp B., Kumánovics A., Li H., Pandey A., Billadeau D., Sadighi Akha A.
| Disease area | Application area | Sample type | Products |
|---|---|---|---|
Immunological & Inflammatory Diseases | Pathophysiology | Plasma |  Olink Explore 3072/384 |
Abstract
Background
The few reported patients with pathogenic IRF8 variants have manifested 2 distinct phenotypes: (1) an autosomal recessive severe immunodeficiency with significant neutrophilia and absence of or significant decrease in monocytes and dendritic cells and (2) a dominant-negative form with only a decrease in conventional type 2 dendritic cells (cDC2s) and susceptibility to mycobacterial disease.
Objectives
Genetic testing of a child with persistent EBV viremia identified a novel IRF8 variant: c.1279dupT (p.∗427Leuext∗42). The variant was also found in his mother, who was subsequently diagnosed with a human papillomavirus-positive tumor. We sought to examine the pathogenicity of the identified IRF8 variant and its phenotypic and functional characteristics.
Methods
Immunophenotypic and functional flow cytometry, natural killer cell cytotoxicity, matrix-assisted laser desorption/ionization–time of flight mass spectrometry, T-cell receptor Vβ spectratyping, Sanger sequencing, RNA-sequencing, Olink proteomics, immunoblotting, molecular cloning, dual-luciferase reporter assay, immunofluorescence microscopy, and image analysis.
Results
The 42 amino acid C-terminal extension of the mutant IRF8 (∼4 kDa heavier than wild type) impaired IRF8 nuclear localization in a dominant-negative manner and inhibited IRF1/IRF8-mediated transcriptional activities. Both patients had a decrease in plasmacytoid dendritic cells (pDCs) and in cDC1s, a mild neutrophilia and a mild monocytosis. Their existing pDCs had impaired IFN-α production. On TLR engagement, the production of IL-1β, IL-6, IL-10, and IL-12 by their monocytes and of IL-12 by their myeloid DCs were within normal limits. Natural killer cell development and cytolytic activity were essentially normal. RNA-sequencing and proteomic approaches bolstered the phenotypic and functional findings.
Conclusions
This study defines the pathogenic nature of the c.1279dupT (p.∗427Leuext∗42) IRF8 variant, determines its dominant-negative mechanism of action, and broadens the existing phenotype of human IRF8 immunodeficiency.