Cytomegalovirus Infection In Renal Recipients And Its Influence On Transplanted Kidneys

Recent improvements in immunosuppression have led to a dramatic increase in short-term renal allograft survival. However, though irnmunosuppressive agents which are sufficient to prevent acute rejection have been used, so-far the long-term result of renal transplant has not improved correspondingly. The rate of graft loss in the late posttransplantation period has remained virtually unchanged. The average half-life of a transplanted kidney is still 7-10 years. It is common that that renal function becomes depleted and dialysis is resumed, one or several years after transplantation. The reasons that have caused this phenomenon are not clear. Pathological investigation has shown that this kind of kidney has obvious scar trend. The allografts demonstrate extracellular matrix deposition, interstitial fibrosis and renal tubule atrophy on pathology. But all of the pathologic alterations are nonspecific. A lot of immunity and non-immune factors may finally cause the changes mentioned above. Depending simply on the pathologic alterations, it is very difficult to determine the reasons for the pathologic alterations. For this reason, the term "chronic allograft nephropathy (CAN)" which does not refer to etiological factors is used to define all the clinical disorders above-mentioned. CAN is the principal cause of late graft loss after the first year of renal transplantation. However, in recent years animals' experiments show that CMV infection is also an important cause of CAN. It was found that CMV infection accelerates and enhances histologic changes in CAN, especially interstitial fibrosis and collagen synthesis, in a rat model of renal transplantation.Cytomegalovirus (CMV) is a common virus pathogen which infects human beings. The virus can invade into human bodies through multiple channels, such as respiratory track, digestive system, blood transfusion and organ transplantation, etc.. Epithelial cells, endothelial cells of blood vessels, and leukocytes in peripheral blood are extremely easy to be infected. 60-90% of healthy adults have been infected with CMV. Cytomegalovirus is a very weak poisonous pathogen for a healthy individual whose immunity is normal, but, once infected, the host will carry Cytomegalovirus for the remainder of his life. As theimmune function of an organism drops, especially when cellular immunity is low, the body can become infected by CMV newly, or the virus that was hidden in the body can be reactivated, duplicated again, and form active CMV infection. CMV often forms dual or multiple infections with other pathogens, the condition is critical, and infected individuals have high mortality.As heavy doses of immunosuppressive agents have been used in early post-transplant, active CMV infection is up to 60- 80%. 15-35% of those infections are CMV disease which shows some symptoms. For this reason, active CMV infection is considered not only the main cause for death of recipients early after kidney transplant, but it might also relate to the dysfunction of transplanted kidneys in the long term after transplantation. In order to get better results from kidney transplantation, prevention and treatment of active CMV infection effectively, and in time, may play an important role.Under the normal situation, so long as CMV-IgM can be found in serum, CMV-IgG becomes positive from negtive, or the concentration of CMV-IgG grows over four folds, the diagnosis of active CMV infection can be determined. However, as heavy doses of immunosuppressive agents have been used in early post-transplant, this kind of patient has had little ability to produce antibodies. Relying on serology tests can't provide correct diagnosis for active CMV infection in this special group of people. In order to overcome the difficulty existing in diagnosis of active CMV infection, in recent years a new approach in which CMV-pp65 antigen in the leucocyte of periphery blood is detected has been clinically used to determine if active CMV infection exists. The antigen pp65 is a phosphoric acid protein formed by 561 pieces of amino a...