The importance of glomerular deposits of von Willebrand factor in human renal allografts.

Objective: The aim of this study was to evaluate the importance of glomerular expression of von Willebrand factor (vWF) in human renal allografts.

Methods: We investigated graft biopsies from 72 renal transplant recipients, 40 with acute rejection (AR) and 32 with chronic allograft nephropathy (CAN). All biopsy specimens were immunostained with vWF and CD68 and graded using 3-tiered scales. The follow-up biopsies of patients with AR were reevaluated for development of glomerular sclerosis.

Results: A significant difference was found between type 1 and type 2 AR with regard to glomerular vWF expression (P < 0.01). None of the patients with type 1 AR showed mesangial vWF expression, but 36.4% of patients with type 2 AR showed segmental mesangial vWF expression. In follow-up biopsies, 18 of 40 patients developed significant glomerular sclerosis, and patients with mesangial vWF expression (grade 3 GvWF) showed glomerular sclerosis earlier than did others (P < 0.01). In addition, the outcome for grafts that showed grade 3 glomerular vWF was significantly worse than was the outcome noted for grafts that showed grade 1 or grade 2 glomerular vWF (P < 0.001). Half of the biopsy specimens in the CAN group showed global mesangial vWF expression. Glomerular macrophage infiltration was correlated with degree of glomerular vWF expression both in the AR and in the CAN groups (P < 0.05, P= 0.001, respectively).

Conclusion: We hypothesized that the increasing amount of glomerular vWF may be used as a marker of acute vascular rejection and may help for the evaluation of renal allograft biopsies without sufficient arteries. In addition, it can also be a marker for development of early glomerular sclerosis and may help us determine which patients are in need of further treatment.