Which are the causes of Graft Versus Host Disease?

Graft Versus Host Disease (GVHD) is a condition that occurs after a stem cell or bone marrow transplant, where the donor's immune cells attack the recipient's tissues. This immune response can cause significant damage to various organs and systems in the body. GVHD can be classified into acute or chronic, depending on the time of onset and duration of symptoms.

The causes of GVHD can be attributed to several factors:

1. HLA mismatch: The human leukocyte antigen (HLA) system plays a crucial role in the immune response. When the donor and recipient have different HLA types, the immune cells from the donor may recognize the recipient's tissues as foreign and initiate an immune response, leading to GVHD.

2. Conditioning regimen: Prior to a transplant, recipients undergo a conditioning regimen that involves high-dose chemotherapy and/or radiation therapy. This conditioning aims to suppress the recipient's immune system and create space for the donor cells. However, it also damages the recipient's tissues, making them more susceptible to attack by the donor's immune cells.

3. Donor-recipient compatibility: The degree of compatibility between the donor and recipient plays a significant role in the development of GVHD. The closer the match, especially in terms of HLA compatibility, the lower the risk of GVHD. In cases where the match is not optimal, the risk of GVHD increases.

4. Donor type: The source of the donor cells can also influence the risk of GVHD. Transplants using cells from related or unrelated donors, or even from cord blood, have different risks of GVHD. For example, unrelated donors may have a higher risk of HLA mismatch, increasing the likelihood of GVHD.

5. Immunological factors: Certain immunological factors, such as the presence of specific immune cell subsets in the donor graft, can impact the development of GVHD. For instance, the presence of mature T cells in the donor graft increases the risk of GVHD, while the depletion of these cells can reduce the risk.

6. Age and comorbidities: The age and overall health of the recipient can influence the risk and severity of GVHD. Older recipients and those with pre-existing medical conditions may have a higher risk of developing GVHD and experiencing more severe symptoms.

It is important to note that GVHD is a complex condition influenced by multiple factors, and the interplay between these factors can vary from case to case. Close monitoring, early detection, and appropriate management are crucial in minimizing the impact of GVHD on transplant recipients.