Abstract: Presence in a recipient of antibodies directed against donor specific antigens represent a major obstacle in transplanting such patients. Removal of these antibodies represents a challenge for physicians dealing with kidney transplantation. Several strategies, techniques and old and new drugs are to date used to desensitize these patients. Desensitization may occur before transplantation or at the time of transplantation or after transplantation according whether physicians deal with living or deceased donors. Different techniques may be used to reveal the presence of antibodies in the recipients; each technique has different sensitivity and specificity, different advantages and disadvantages. The target of the drugs used to desensitize are B cells, Plasma cells, the antibodies themselves and finally, the complement that is the final actor causing tissue disruption. If B cells are relatively easy to be targeted, more difficult are the plasma cell. Indeed, several new drugs are used in randomized trials also to defeat plasma cells. Antibodies may be removed rather easily, but often their removal is followed by a rebound. Complement is not easy to be defeated and new drugs are to date used to be successful in this action. However is to date possible to desensitize many patients and to obtain successful transplantation.

Abstract Kidney transplant recipients, because of a weak immune response due to the assumption of immunosuppressant are exposed to the risk of COVID-19 infection. This fact realize the problem on how to treat the severe infection without carrying the risk of acute rejection due to the reduction of the immunosuppressive drugs. The best are the prophylactic measures to be taken before transplantation as vaccination. If the patient is already transplanted, three measures may be undertaken: Vaccination, use of monoclonal antibodies, use of therapeutic antiviral small molecules. Concerning vaccination is still debated which one is the best and how many doses should be given. The surge of new virus variant is the major problem and invites to find new active vaccines. In addition, not all the transplanted patients develop antibodies. The other measure is the use of monoclonal antibodies. They may be used as prophylaxis or in the early stage of the disease. Finally, the antiviral small molecules may be used again as prophylaxis or treatment. Their major drawback are the interference with the immunosuppressive drugs and the fact that some of them cannot be administered to patients with low eGFR.