Dendritic cells (DC ) are the most important antigen-presenting cells (APCs ) to T lymphocytes ripeness DC cells is crucial for the type of T cell response Immature DC induces cell tolerance state , while the mature cell DC - a full immune response. This is very important in transplantation , and in particular of graft rejection reactions after organ transplantation . DC donor cell presents the antigen in a direct way , whereas DC recipient cell in an indirect way . DC cells are immature or tolerogenic properties may prolong allograft survival .

Toll-like receptors (TLRs) play a fundamental role in the induction of immune responses. They are richly represented in these places the body, which are a potential gateway infection. The locations of these TLRs, mainly present on antigen presenting cells (APC) and certain non-immune cells, especially epithelial cells, are able to recognize molecular patterns (PAMP) infiltrating the local pathogens and initiate the defensive response. TLRs are therefore an important component of the innate response.

Studies of a few last years give evidence for a role of apoptosis not only in graft rejection but also in induction of transplantation tolerance. Apoptosis – programmed cell death is an active process which refers to superflous and defective cells. For a responsiveness to allograft the most important are two mechanisms of apoptosis: AICD (activation induced cell death) which involves Fas/FasL engage- ment and PCD (passive cell death) – caused by cytokine withdrawal. Graft rejection is caused by genetic differences between a donor and a recipient.