Recent groundbreaking medical advances in post-transplant management have significantly boosted the success rates of transplantation procedures. The British Society for Immunology defines transplantation as the process by which viable cells, tissues, or organs are moved from one site to another to replace or repair organs and tissues that are diseased or damaged (Lai et al., 2021). However, transplant rejection remains a critical challenge in this field. Most of the transplant rejection mechanisms occur due to immune system responses against the allograft or, of the allograft against the recipients. This research provides an overview of transplant rejection, exploring some of the mechanisms involved.
Transplantation rejection can be broadly classified into three categories: hyperacute rejection, acute and chronic rejection (Vaillant, & Mohseni, 2020). In hyperacute rejection, specific antibodies attack the graft typically within minutes or a few hours after grafting. It is believed to occur due to the presence of cytotoxic antibodies in the recipient responding to tissue antigens on the donor allograft (Kenta & Takaaki, 2020). On the other hand, acute rejection occurs after a few days or weeks after transplantation. It is usually caused by specific lymphocytes acting against human leukocyte antigens present in the grafted tissue or organ. Chronic rejections take months or years after grafting. Kenta & Takaaki (2020) assert that the immune response to an allograft is a continuous conversation between the adaptive and innate immune system that may lead to a rejection of the transplanted organs if no intervention is instituted. Injury to the tissue sustained during organ retrieval or cell isolation and ischemia-reperfusion activate the innate immune system’s elements, thus initiating and amplifying adaptive response. The immunopathogenesis of such rejections is essentially occasioned by several mechanisms involving chronic inflammation, cellular and humoral immune reactions (Vaillant, & Mohseni, 2020). These different mechanisms occur depending on the type of allograft transplanted.
Based on available clinical evidence, preventive measures have been preferred in tackling transplant rejection. Donor and recipient matching by considering tissue typing, blood groups of the participants, and the recipient’s blood serum-donor cells reaction are widely used. Matching is undertaken to ensure the donor-recipient antigens are as similar as possible to minimize the risk of allograft rejection. In addition, immunosuppressive drugs are employed to dampen the possible adverse immune response. (Lai et al., 2021). Furthermore, further research is ongoing on the immunological mechanisms of rejection to better understand cross-matching in diagnosis and treatment and new prevention strategies.
References
Lai, X., Zheng, X., Mathew, J. M., Gallon, L., Leventhal, J. R., & Zhang, Z. J. (2021). Tackling chronic kidney transplant rejection: Challenges and promises. Frontiers in Immunology, 12, 1755. Web.
Vaillant, A. A. J., & Mohseni, M. (2020). Chronic transplantation rejection. PubMed. Web.
Kenta, I., & Takaaki, K. (2020). Molecular mechanisms of antibody-mediated rejection and accommodation in organ transplantation. Nephron, 144(1), 2-6.