What is the significance of 'graft' in graft-versus-host disease in the context of HSCT?

In the context of graft-versus-host disease (GVHD) associated with hematopoietic stem cell transplantation (HSCT), the term 'graft' specifically refers to the stem cells that are transplanted from a donor to a recipient. These stem cells have the potential to differentiate into various blood cell types and can initiate immune responses.

When the donor’s immune cells, which are part of the graft, recognize the recipient's tissues as foreign, they can mount an attack against those tissues, leading to GVHD. This condition is a significant complication following HSCT, particularly when the donor and recipient are not perfectly matched. The immunological response is primarily mediated by donor T cells present in the graft, emphasizing the importance of the graft's origin and composition in the risk of developing GVHD.

The other options misinterpret or narrow the definition of 'graft' in this context, focusing either improperly on the components of transfusion or limiting the concept to skin grafts or surface health indicators of the donor, none of which accurately capture the essence of what 'graft' refers to in GVHD.