What can minor histocompatibility antigens (mHags) cause after a transplant?

Minor histocompatibility antigens (mHags) play a significant role in transplant immunology, particularly in the context of mismatched grafts. These antigens can trigger immune responses because they are recognized as foreign by the recipient's immune system. When mHags are present and not matched between the donor and recipient, the recipient's immune cells can mount an attack against the transplanted tissue. This immune response can lead to graft-versus-host disease (GVHD), where the donor immune cells recognize the recipient's tissues as foreign, causing inflammation and damage. Furthermore, the reaction to mHags can also contribute to the potential failure of the graft due to rejection processes initiated by the recipient's immune system.

In contrast to other options, the presence of mHags typically does not enhance immune tolerance or contribute positively to graft acceptance. Instead, they are more associated with adverse outcomes such as graft-versus-host disease and the risk of graft failure. Understanding the influence of minor histocompatibility antigens is crucial for improving transplant outcomes and managing patient care post-transplantation.