Summary: The innate immune processes proceeding in organ allografts and their contribution to acute and chronic rejection have been described. Ischemia/reperfusion phenomenon with damage of the endothelial and parenchymal cells and reaction of granulocytes and
macrophages as well as humoral factors including complement, coagulation factors, free radicals, nitrous oxide have an impact on late function of the transplanted organs. Participation of granulocytes and macrophages in acute allogeneic rejection is another example of the role of the innate system in transplant damage. Recurrent basic disease, diabetes, hyperlipidemia, adverse effects of immunosuppressive drugs in allograft recipients are factors evoking reaction of the innate system. Investigations of the innate immune system have shown an essential role, beside of the adaptive system stimulated by allogeneic mismatch, in organ graft rejection.

Keywords: innate immunity, adaptive immunity, Allotransplantation