Detection of engraftment of donor-derived antibody producing cells in a lung transplant recipient by anti-cytomegalovirus IgG avidity test.

Transplant recipients become immunocompromised through the use of immunosuppressive therapy to prevent allograft rejection. These recipients readily experience human cytomegalovirus (CMV) infection or reactivation. Therefore, CMV represents a life-threatening pathogen in transplant recipients. To demonstrate the serostatus and course of IgG maturation against CMV in transplant patients, we measured the transition of anti-CMV IgG and its affinity (avidity index; AI) as criteria for antibody maturation. Among 31 lung transplant recipients, 26 were infected with CMV before transplantation and maintained anti-CMV IgG and high AI values throughout the study period. Four of the 31 experienced primary infection with CMV through the allograft, with two of the 4 recipients presented high AI values even after 6 month post-transplantation. A significant portion of donor-derived plasma cells were detectable in one recipient. These results suggested that the plasma cells from donors are carried in through the transplanted lung and lymph nodes and produce matured high-avidity IgG from the early stage of transplantation.