Evaluation by histology, immunohistology and PCR of protocollized renal biopsies 1 week post-transplant in relation to subsequent rejection episodes

Renal biopsies were performed 1 week following renal transplantation at a time without clinical evidence of rejection in 43 patients (13 females, mean age 48 years range 18-60 and 30 males, mean age 43 years range 17-59 years). Thirty-six biopsies were available for histological or immunohistochemical analysis. Immunohistochemical analyses were performed with monoclonal antibodies against leukocytes (CD45), monocytes (WT14), complement factor 3 (C3), T-cells (Leu4), T-cell receptor alpha beta and gamma delta, tumour necrosis factor alpha (TNF alpha), IL-2 receptor (IL2-R, TAC), intercellular adhesion molecule-1 (ICAM1) and HLA-DR. The slides were scored semiquantitatively with the observers having no knowledge of clinical or patient data. TNF alpha and IL-2R were also measured by quantative PCR. None of the studied parameters correlated to delayed graft function or graft loss. Histological analysis showed that both focal interstitial infiltrate (18/35) and tubular basement membrane disruption (11/35) were followed by a higher incidence of subsequent rejection (P = 0.03 and 0.02 respectively). Also positivity for WT14 around tubuli (P = 0.02) was associated with subsequent occurrence of rejection. The intensity of staining of ICAM-1 on PTC as well as TAC on proximal tubular cells was associated with the number of subsequent rejection episodes. The association between the IL-2 receptor and subsequent rejection was also found applying PCR to the tissue specimens. We conclude that the presence of focal interstitial infiltrates and tubulitis in 1-week biopsies from well-functioning grafts carries an increased risk of subsequent rejection.