Complement activation and vascular complications after pediatric allogeneic hematopoietic stem cell transplantation

Area of Science:

• Hematology
• Immunology
• Pediatric Medicine

Background:

• Treatment-related toxicity is a major challenge in pediatric hematopoietic stem cell transplantation (HSCT).
• Understanding the role of the complement system in HSCT complications is crucial for improving patient outcomes.

Purpose of the Study:

• To investigate the activation of the complement system during and after pediatric HSCT.
• To analyze the relationship between complement activation and acute adverse events, including vascular complications.

Main Methods:

• Prospective, single-center study of 42 pediatric HSCT patients.
• Plasma C3a and SC5b-9 levels were measured peri- and post-transplant.
• Acute adverse events and vascular complications were monitored and analyzed.

Main Results:

• High incidence of adverse events (92.9%) and severe events (54.8%) within 100 days post-HSCT.
• Capillary leak syndrome (CLS), veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS), or thrombotic microangiopathy (TMA) occurred in 9.5% of patients.
• Complement activation, indicated by increased C3a, occurred peri-transplant.
• Elevated SC5b-9 levels were observed in 10 patients, but showed no clear correlation with adverse events, except in one severe TMA case.

Conclusions:

• Terminal complement activation appears specifically linked to clinically significant HSCT-associated TMA.
• Further research is needed to elucidate the precise role of complement activation in other HSCT toxicities.