INTERSTITIAL REJECTION, VASCULAR REJECTION, AND DIFFUSE THROMBOSIS OFRENAL-ALLOGRAFTS - PREDISPOSING FACTORS, HISTOLOGY, IMMUNOHISTOCHEMISTRY, AND RELATION TO OUTCOME

Histological and immunohistochemical analyses were made of biopsy spec imens from 50 consecutive patients who experienced putative graft reje ction, The mean age of the patients was 44.5 years (range, 17-69 years ) and 26 were men. There were 67 evaluable allograft specimens, which were grouped according to the histological diagnosis: group 1, acute t ubulointerstitial rejection (n=42); group 2, acute vascular rejection (n=18); and group 3, diffuse thrombosis (n=7), Over a follow-up period of 21-57 months, the mean number of rejection episodes was 1.7, 2.8, and 3.3 in groups 1, 2, and 3, respectively, Allograft loss occurred i n 7 out of 30, 10 out of 16, and 4 out of 4 patients in groups 1, 2, a nd 3, respectively. The following histological parameters differed sig nificantly (P<0,05) among the groups: interstitial edema, congestion o f peritubular capillaries, glomerular thrombosis, and glomerular ische mia (group 3 > group 2 > group 1). Interstitial bleeding was seen more often in group 2 and 3 tissues than in group 1 specimens (P<0,01), Im munohistochemical analyses showed that vascular rejection was associat ed with WT14 staining for monocytes and macrophages around the tubuli and with interstitial deposition of complement factor 3, With regard t o serology, positive anti-endothelial cell antibody-dependent cellular cytotoxicity was associated with vascular rejection and thrombosis of the graft in all patients tested, and with graft loss in 75%. Pre-exi stent positive anti-IgG immunofluorescence on peritubular capillaries in pretransplant biopsy specimens incubated with patient serum was fou nd in only 3 of the 50 patients, but was associated with graft loss in 2 of the 3. Cytomegalovirus infection was associated with a higher pe rcentage of graft loss, There were significant intergroup differences in panel reactive antibodies before transplantation (P<0,001), with hi gher titers in groups 2 and 3, The findings in relation to interstitia l rejection are compatible with cellular rejection, while the data on vascular rejection support a humorally mediated pathogenesis.