What mediates Graft vs Host Disease (GVHD)?

Graft vs Host Disease (GVHD) primarily involves T cells, which mediate the immune response against the recipient’s tissues after an allogenic transplant. In GVHD, donor T cells recognize the recipient’s tissues as foreign and initiate an inflammatory response. These T cells proliferate and activate, leading to the damage of host tissues, particularly affecting the skin, liver, and gastrointestinal tract.

The process begins when the donor T cells encounter discrepancies in major and minor histocompatibility antigens between themselves and the recipient. Activated donor T cells secrete cytokines that further enhance the immune response and recruit other immune cells to the site of action, amplifying the inflammatory response.

In contrast to T cells, B cells primarily mediate humoral immunity through antibody production, but they are not the main players in the acute phases of GVHD. Similarly, while macrophages and neutrophils play roles in the immune system and can contribute to the inflammatory process, it is the T cells that are specifically responsible for the recognition and initiation of tissue damage in GVHD.