Background: The aim of this study was to determine the significance of the renal expression of ICAM-1 in IgA nephropathy (IgAN).
Patients and method: First, we identified ICAM-1 (CD54) expression in tubular epithelial cells and interstitial leucocytes in renal biopsies from 45 patients with IgAN and 29 patients with non-glomerulonephritis nephropathy (non-GN). We then analysed the relationship between this expression and both histological and clinical data at the time of renal biopsy and after 2.4 (2) (X [SD]) years in IgAN, and 1.8 (1.5) years in non-GN.
Results: In IgAN, tubular ICAM-1 positive staining was seen in 25 (55%) biopsies; it was associated with extracapillary proliferation, glomerulosclerosis involving less than 50% of glomerular area, interstitial cell infiltration and tubular atrophy. ICAM-1 positive interstitial leucocytes were 234 (307)/mm2; this expression correlated with glomerulosclerosis, tubular atrophy, interstitial fibrosis and serum creatinine (Cr) level. In patients with 50% increase in Cr level, ICAM-1 positive interstitial leucocytes were 516 (360)/mm2 as compared with 66 (87.8)/mm2 (U = 16; p < 0.005) in patients with stable Cr. In non-GN, tubular ICAM-1 expression was observed in 7 (24%) biopsies.
Conclusions: Tubular and Interstitial expression of ICAM-1 can be a marker of tubulointerstitial damage in IgAN. Interstitial ICAM-1, rather than tubular ICAM-1, may predict the progression of this disease.