Does the risk of acute rejection really decrease with increasing recipient age?

In corneal transplants the risks of acute rejection and graft failure decrease with increasing recipient age, but kidney graft survival analyses tend to show the opposite effect. Why is this? Cadaveric kidney transplants performed in the UK and Republic of Ireland between 1985 and 1993 (UKTSSA database) were analysed by multifactorial methods to identify major factors affecting graft survival. In a study database that had been censured for technical failure and death with a functioning transplant, it was shown that increasing recipient age was associated with decreasing risk of graft failure at 1 year. This is consistent with the view that kidney transplants, like corneal transplants, are less likely to be acutely rejected as the age of the recipient increases.