Impact of donor and recipient human cytomegalovirus status on kidney transplantation.

Human cytomegalovirus (HCMV) is considered to be a major pathogen that affects the outcome of solid organ transplantation (TX). Both recipient and donor may be HCMV positive, therefore HCMV re-infection is possible after TX. However, little is known how cytomegalovirus (CMV) transmitted from an infected donor to an infected recipient modulates the recipient's already suppressed immunity, and what the clinical consequences are. To investigate these issues, 52 kidney recipients were followed up for 2 years after TX. T, B and natural killer (NK) lymphocytes, naive and memory T subsets, CD28 expression, relative telomere length, CMV-specific lymphocytes and serum cytokines were measured several times post-TX. Patients were monitored for signs of CMV viremia and other infections. The most important observation was that CMV-specific lymphocytes expand vastly in HCMV-infected recipients who received kidneys from infected donors, in comparison with uninfected donors. Despite this, a higher rate of HCMV viremia was found. Immune deterioration was confirmed by an increased number of CD28-negative T lymphocytes, inverted CD4/CD8 index and shortened telomeres. This was superior in HCMV-infected recipients transplanted from infected donors, when compared with uninfected. In conclusion, CMV alters the immune system in kidney transplant recipients and promotes immune exhaustion.