[Time course of morphological changes in humoral renal allograft rejection in ABO incompatibility between donor and...

One hundred and five biopsy specimens taken in different periods after 34 ABO-incompatible mismatched related kidney transplantations were examined to establish the patterns of humoral activity from the morphological changes and expression of C4d deposits in the peritubular capillaries. Severe reversible forms of acute humoral rejection (AHR) (2 patients) and minimal morphological manifestations (13 patients) were observed in the biopsy specimens taken as long as 2 months later in Group 1 (C4d+). In the early period, the minimal manifestations of AHR did not cause organ dysfunction; but in the late period, 5 of them developed chronic humoral rejection in persistent humoral activity; 4 grafts were removed 531,720, 1019, and 1252 days later. Group 2 (C4d-) (n = 19) showed no graft losses or significant chronic changes; the late minimal manifestations of AHR had no impact on the duration of organ function in 3 recipients. The timely detection of early humoral activity and minimal manifestations of AHR is needed for the measures taken to reduce a risk for late function loss of the grafted organ.