What is one reason why HSCT patients might experience different GVHD outcomes compared to transfusion recipients?

HSCT, or hematopoietic stem cell transplantation, involves the transplantation of stem cells to replace a patient's damaged or diseased immune system, which is particularly relevant in treating conditions like leukemia and other hematological disorders. One critical reason that HSCT patients might experience different outcomes with GVHD (graft-versus-host disease) compared to transfusion recipients is precisely because HSCT involves a complete immune system replacement.

In HSCT, donor cells are introduced to the recipient's body, and these cells can recognize the recipient's tissues as foreign, potentially leading to GVHD. This is particularly pronounced because the stem cells given to the patient reconstitute the entire immune system, including T cells, which are responsible for the immune response. As the newly introduced immune cells mount an attack on what they perceive as foreign host tissues, the risk of developing GVHD is significantly heightened compared to transfusion recipients, who receive blood products that generally contain fewer immune cells.

Transfusion recipients typically receive only red blood cells, platelets, or plasma, with most of the immune cells being filtered out before transfusion. Therefore, the chance of developing a significant immune response like GVHD is much lower in these patients compared to those undergoing HSCT, where the entire immune