Let’s now discover the immunological mechanisms on which alloreactivity is based!
Antigen presentation is the process by which the body’s cells present, via their HLA molecules, antigen proteins in the form of short peptides to the T-cell TCRs.
T cell activation refers to all the steps necessary for the transformation of a naive T cell into a T cell capable of exercising its functional properties.
B cell activation refers to all the steps necessary for the transformation of a naive B cell into a B cell capable of evolving into a plasma cell secreting immunoglobulins.
NK cell activation corresponds to the triggering of the cytotoxic activity of the NK cell towards a target cell.
Alloreactivity refers to the immunological mechanisms implemented to recognise and destroy cells or components coming from another genetically different individual of the same species.
Cell-mediated rejection is also called TCMR - for “T-Cell Mediated Rejection” - because it is mainly mediated by T cells. It is the consequence of the activation and migration of alloreactive T cells in the graft. NK cells also contribute to cell-mediated rejection.
Humoral rejection is also called ABMR - for “AntiBody Mediated Rejection” - because it is the consequence of antibodies directed against alloantigens expressed by the donor cells, also called DSA (Donor Specific Antibodies).
Ischaemia is the cessation or insufficiency of blood circulation in a part of the body or an organ which deprives cells of oxygen supply and leads to their necrosis.
Reperfusion is the restoration of blood supply to the tissue or organ.
