Morphological studies of baseline needle biopsies from living donor kidneys: Light microscopic, immunohistochemical and ultrastructural findings

Fifty-seven consecutive living donors (31 women and 26 men aged 20.7-72.3 y ears, mean 50.6 years) were subjected to needle biopsy during nephrectomy, immediately before removal of the kidney. By light microscopy, semiquantita tive scoring (0-3) was performed for arteriosclerosis, arteriolar hyalinosi s (hyalin arteriolosclerosis), glomerulosclerosis, interstitial mononuclear cell infiltration, and interstitial fibrosis/tubular atrophy. Whereas vasc ular changes were striking in many biopsies (arteriosclerosis grades 2-3: 2 8/54 cases, arteriolar hyalinosis grades 2-3: 15/55 cases), glomerular and tubulointerstitial changes were mostly low grade. The morphological changes tended to be more pronounced in middle-aged and older individuals, but, in particular, vascular changes were seen also in the younger age group. Immu nofluorescence microscopy revealed glomerular granular staining for IgM in 52.7% of the cases, IgA in 9.1%, IgG in 1.8%, and C3 in 12.7%. The main ult rastructural finding was glomerulosclerosis; one case with diffuse glomerul ar IgA showed distinct dense deposits, and one case showed similar dense de posits without IgA deposition. Arteriolar wall deposition of C3 was found i n 58.2% of the cases, and IgM in 10.9%. Especially C3 occurred both with ar teriolar hyalinosis and in arterioles without light microscopic alterations . The observation of significant vascular changes in baseline biopsies is r elevant especially in the differential diagnosis of chronic rejection and c yclosporine nephropathy. The immunohistochemical findings strongly indicate the occurrence of immunoglobulins and complement factor C3 in both glomeru li and arterioles without clinical or morphological signs of renal disease. The possible pathophysiological significance of such deposits remains, how ever, uncertain.