Comparative distribution of laminin and collagen types I, III and IV in transplant vasculopathy.

Composition of the extracellular matrix (ECM) was studied in transplant vasculopathy occurring in rejected renal allografts using the immunoperoxidase technique with antisera against laminin, and collagen types I, III and IV. In acute transplant vasculopathy the loose ECM network of the intima showed intense immunostaining for laminin and type IV collagen. Type III collagen was detected in the advanced acute cellular intimal proliferations, while early acute lesions did not show immunreactions. Type I collagen was not seen in significant amount. In contrast to these findings in chronic transplant vasculopathy associated with intimal fibrosis the ECM was largely composed of interstitial collagen types III and I, while staining for the basement membrane type ECM components were markedly reduced. Degradation of the matrix components with variable composition was noted in foci of mononuclear infiltrates occurring inside the fibrotic intima. These results indicate that the ECM shows a compositional change in transplant vasculopathy which is associated with the age of the lesion.