Remote immune processes revealed by immune-derived circulating cell-free DNA

Area of Science:

• Immunology
• Genomics
• Biomarker Discovery

Background:

• Conventional blood cell counts do not fully capture immune activity in remote tissues.
• Understanding immune cell dynamics is crucial for diagnosing and monitoring various health conditions.

Purpose of the Study:

• To investigate the utility of immune cell type-specific methylation patterns in circulating cell-free DNA (cfDNA) as a tool for studying human immune cell dynamics.
• To establish cfDNA as a novel biomarker for monitoring immune responses.

Main Methods:

• Characterization of cfDNA released from specific immune cell types in healthy individuals (N=242) using cross-sectional and longitudinal analyses.
• Analysis of cfDNA levels in response to perturbations of immune homeostasis, including influenza vaccination (N=92) and specific diseases (eosinophilic esophagitis N=21, B-cell lymphoma N=27).

Main Results:

• Immune cfDNA levels exhibited dynamic changes, unlike stable blood cell counts, suggesting cfDNA reflects homeostatic cell survival adjustments.
• Selective elevation of immune-derived cfDNA was observed during immune perturbations.
• B-cell-derived cfDNA increased before B-cell count elevation post-vaccination and predicted antibody production efficacy.
• Elevated eosinophil and B-cell cfDNA were detected in patients with eosinophilic esophagitis and B-cell lymphoma, respectively, even when blood cell counts were normal.

Conclusions:

• Immune-derived cfDNA serves as a novel biomarker for monitoring immune responses.
• cfDNA analysis provides insights into immune processes in remote tissues, inaccessible by conventional methods.
• This approach enhances the understanding of immune dynamics in both physiological and pathological conditions.