Acute graft-versus-host disease (aGVHD) remains a significant complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT), often leading to rapid multi-organ failure. Current diagnostic methods largely depend on clinical symptoms and histological confirmation, typically after tissue damage has occurred. This delay in detection means that clinicians frequently miss the optimal window for intervention due to the absence of sensitive and specific early biomarkers.
A recent study published in hLife by Dr. Shunqing Wang and colleagues at Guangzhou First People's Hospital investigated immune changes in 111 allo-HSCT recipients over a period of up to 100 days post-transplant. The researchers monitored various lymphocyte subsets and identified a particular group of activated CD38+HLA-DR+CD8+ T cells that expanded significantly in patients who later developed aGVHD. The study found that when these cells made up more than 36.6% of peripheral blood lymphocytes within the first month after transplantation, it served as an accurate early warning sign for impending aGVHD.
To further assess the role of this cell subset, the team analyzed 20 patients already diagnosed with aGVHD. They noted that patients who responded positively to treatment showed a marked decrease in CD38+HLA-DR+CD8+ T cells as their symptoms improved. Conversely, those whose disease progressed or did not respond to therapy maintained high levels of these cells despite treatment efforts. According to the authors, "simple, repeated flow-cytometric measurement of this subset could function as a 'real-time dashboard' to monitor therapeutic efficacy and support timely adjustment of immunosuppressive regimens."
The researchers also explored whether targeting these pathogenic cells could offer new treatment options. Using a mouse model, they administered daratumumab—an anti-CD38 monoclonal antibody already approved for multiple myeloma—to selectively deplete CD38-expressing CD8+ T cells. The results showed that daratumumab effectively removed these cells, reduced tissue damage, and improved survival rates among treated animals.
Further mechanistic studies indicated that activation of these CD8+ T cells does not rely on traditional T-cell receptor recognition but is instead driven by inflammatory cytokine IL-15 through the PI3K/mTOR signaling pathway. Once activated, these cells express NKG2D receptors and target stress-induced ligands such as MIC-α on tissues, resulting in cytotoxic effects even without strong antigen stimulation.
The study concludes that monitoring CD38+HLA-DR+CD8+ T cell levels can help predict risk before symptoms appear, track treatment response dynamically, and guide targeted therapies such as daratumumab for precise intervention against aGVHD. As stated by the authors: "By shifting immune surveillance for aGVHD from 'after symptoms' to 'before symptoms', this work provides a new paradigm for managing transplant-related immune complications and may inspire similar strategies in other T-cell-mediated diseases."
