Unmasking a B-Cell Linkage Phenotype in Severe Acute Meningoencephalitis: A Case Report of IVIG and HydroBox-assisted Immunomodulatory Therapy.

BACKGROUND/AIM: Severe acute meningoencephalitis is a life-threatening neurological condition frequently associated with excessive inflammation, immune dysregulation, and secondary immune dysfunction. Immune exhaustion and abnormal immune cell remodeling may contribute to persistent inflammation and impaired recovery. Molecular hydrogen has emerged as a potential adjunctive therapy due to its selective antioxidant and immunomodulatory properties. CASE REPORT: A previously healthy 30-year-old male developed fulminant acute meningoencephalitis complicated by coma, respiratory failure, and severe systemic inflammation. Longitudinal immune profiling revealed profound immune dysregulation, including extensive T-cell exhaustion-associated phenotypes, abnormal regulatory T-cell remodeling, and marked humoral immune activation. The patient demonstrated widespread expression of inhibitory immune checkpoint markers, accompanied by excessive plasmablast expansion and impaired antibody homeostasis. A combined therapeutic strategy consisting of standard intensive care, intravenous immunoglobulin (IVIG), and molecular hydrogen-based adjunctive therapy (HydroBox strategy) was initiated. Following intervention, systemic inflammation rapidly resolved, immune profiles progressively normalized, and neurological function recovered completely. CONCLUSION: This case highlights the dynamic relationship between acute neuroinflammation and systemic immune remodeling in severe meningoencephalitis. Longitudinal immunophenotyping may provide valuable insights into disease-associated immune dysfunction and therapeutic response. The combination of IVIG and molecular hydrogen-based adjunctive therapy may represent a potential strategy for restoring immune homeostasis in critical neuroinflammatory conditions, warranting further investigation.