The function of pulmonary allografts is regularly impaired by alloimmune reactions with quite variable clinical outcomes, different involved effector cells and molecules, as well as affected anatomical compartments. Acute rejection of grafts after lung transplantation (LuTx) is not only associated with the subsequent development of acute graft dysfunction, but can also contribute - among other immunological and nonimmunological factors - to the development of chronic lung allograft dysfunction (CLAD), which is the main reason for the limited long-term survival after LuTx. In addition to ACR and analogous to other solid organ transplants, the importance of antibody-mediated (humoral) rejection (AMR) in LuTx has also been recognized. There are currently no specific laboratory, radiological, or clinical tests available for either ACR or AMR. Only by the synoptic examination of histopathological changes and interpretation against the background of microbiological, virological, serological, and functional findings, can adequate sensitivity and specificity be achieved in the diagnostics of rejection. In this article, the current criteria for histopathological diagnostics of rejection following LuTx are summarized and the most important differential diagnoses are discussed.
Keywords: Allografts; Antibodies; Graft rejection; Lung transplantation; Pathology.