# Molecular Hydrogen as a Promising Therapy Could Be Linked With Increased Resting Treg Cells or Decreased Fas+ T Cell Subsets in a IgG4-PF-ILD Patient: A Case Report.
> IgG4関連進行性線維化間質性肺疾患患者における水素吸入後の制御性T細胞増加およびFas陽性T細胞サブセット減少：症例報告


## Abstract

An 85-year-old female with suspected IgG4-related progressive fibrosing interstitial lung disease (PF-ILD) complicated by hospital-acquired pneumonia received molecular hydrogen inhalation. By the fourth day, chest X-ray imaging revealed a reduction in pulmonary infiltrations, and the patient began progressing toward mechanical ventilation weaning. Immune phenotyping conducted before and after hydrogen exposure showed a marked elevation in resting regulatory T cell (Treg) counts alongside a substantial decline in Fas-positive helper T cell and cytotoxic T cell subsets. These immunological shifts suggest that molecular hydrogen may modulate immune responses in PF-ILD through anti-inflammatory and antioxidant mechanisms, warranting further investigation in larger patient cohorts.

### Mechanism

Molecular hydrogen is proposed to exert anti-inflammatory and antioxidant effects that upregulate resting regulatory T cells while downregulating Fas-positive helper and cytotoxic T cell subsets, thereby modulating immune-mediated pulmonary fibrosis.

## Bibliographic

- **Authors**: Lui SW, Lu J, Ho YJ, Tang SE, Ko KH, Hsieh TY, et al.
- **Journal**: In Vivo
- **Year**: 2024
- **PMID**: [38688598](https://pubmed.ncbi.nlm.nih.gov/38688598/)
- **DOI**: [10.21873/invivo.13600](https://doi.org/10.21873/invivo.13600)
- **PMC**: [PMC11059909](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11059909/)
- **Study type**: human case report
- **Delivery route**: inhalation
- **Effect reported**: positive

## Delivery context

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

## Safety notes

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [LFL / UFL terminology](https://h2-papers.org/en/safety-notes/lfl-ufl-explained)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 38688598. https://h2-papers.org/en/papers/38688598
> **Source**: PubMed PMID [38688598](https://pubmed.ncbi.nlm.nih.gov/38688598/)