Renal expression of ICAM-1 in IgA nephropathy. A marker of tubulointersticial injury

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 tubul ar epithelial cells and interstitial leucocytes in renal biopsies from 45 p atients 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%) bio psies; it was associated with extracapillary proliferation, glomerulosclero sis involving less than 50% of glomerular area, interstitial cell infiltrat ion and tubular atrophy. ICAM-1 positive interstitial leucocytes were 234 ( 307)/mm(2); this expression correlated with glomerulosclerosis, tubular atr ophy, interstitial fibrosis and serum creatinine (Cr) level. In patients wi th 50% increase in Cr level, 2 2 as compared with 66 (87.8)/mm(2) ICAM-1 po sitive interstitial leucocytes were 516 (360)/mm(2) (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 tubu lar ICAM-1, may predict the progression of this disease.