[Longitudinal study of histocompatibility antigen expression in renal transplants followed for 10 years]

Using monoclonal antibodies against class I and class II (DR antigen) major histocompatibility complex antigens, 65 renal transplant biopsies from 21 recipients whose renal transplants survived ten years or more were studied. Seven biopsies were performed while acute rejection of the renal transplant was under way. The other biopsies were carried out on a routine basis, 6 months (10 biopsies), 2 years (15 biopsies), 4 years (12 biopsies), and 10 years (21 biopsies) after transplantation. Semiquantitative evaluation of fibrous tubulointerstitial lesions was carried out on the biopsies taken after ten years. During episodes of acute rejection, strong expression of class I and class II HLA molecules by transplant tubule epithelial cells was found. When there was no acute rejection, tubule expression of class I and class II HLA molecules was more common in earlier biopsies as compared with later biopsies. In the long-term, persistence of DR antigen in tubule epithelium was associated with increased severity of fibrous tubulointerstitial lesions. A last remarkable finding in some patients was loss of expression of class I antigens in tubule cells from transplants with the longest survivals.