<unk> es <unk>  are a concept in transplantation medicine and describe the presence of antibodies<unk>  to the<unk> 's HLA-Molecules. These antibodies can cause antibody-mediated rejection and are therefore considered a contraindication against transplantation in most cases.<unk>  are a result of B cell and plasma cell activation and bind to HLA and/or non-HLA molecules on the endothelium of the graft. They were first described in 1969 by Patel et al., who found that Transplant recipients who were positively tested for<unk>  using a complement-dependent cytotoxicity crossmatch assay had a higher risk of transplant rejection.<unk>  can either be pre-formed (e.g. by pregnancy, prior transplantation or blood transfusion) or can be formed as a response to the transplantion. (De novo<unk>  Almost a third of patients who are waitlisted for transplantation may have a degree of pre-formed<unk> . Pre-formed antibodies increase the chances of immunological failure of the allograft by causing positive crossmatches and, thereby, result in the exclusion of<unk> s. For patients with pre-formed<unk> , successful transplantation can still be possible by employing strategies such as desensitisation, paired exchange and acceptable mismatching. __TOC__
Donor-specific antibody
Heterophile antibody
Panel-reactive antibody
Human leukocyte antigen
Neutralizing antibody
Antibody
Microantibody
Isoantibodies