Functionele eigenschappen van HLA-moleculen

The success of stem cell and organ transplantation is predominantly determined by the extent of histocompatibility between patient and donor. In case insufficient histocompatibility exists between patient and donor, rejection may occur after organ transplantation whereas graft-versus-host disease may occur after stem cell transplantation. The most important molecules which determine histocompatibility are the HLA-molecules. Functionally, these proteins present parts of other proteins (peptides) to T cells which initiates immune responses. In addition, HLA-molecules act as ligand for killer immunoglobulin-like receptors (KIRs), which are expressed on the surface of natural (NK) killer cells and regulate their cytotoxic activity.Both functional properties of HLA-molecules -antigen presentation and regulation of NK cell activity- play an important role in transplantation.