[Tubulointerstitial nephropathy secondary to collagen-vascular diseases].

Although collagen-vascular diseases mainly affect glomeruli and vessels, tubulointerstitial (TI) involvements as well, are frequently demonstrated histologically. In renal biopsy specimens from patients with lupus erythematosus, tubular atrophy, mononuclear (MN) cell infiltration into the interstitium and interstitial fibrosis are demonstrated in nearly 50% of cases. Immunoglobulins and complement components are sometimes deposited along tubular basement membrane, suggesting an immune-complex mediated mechanism. Infiltrating cells are mainly T cells, but the surface marker studies are not conclusive as to the subset of T cells responsible for the inflammation. As for Sjögren syndrome, TI changes and renal tubular acidosis are the prominent features of the disease. MN cell infiltration in the renal interstitium is also reported in patients with systemic vasculitis.