Quantitative analysis of interstitial alterations in lupus nephritis.

Ninety-eight patients with lupus nephritis followed up for 3 years or more since initial biopsy were the subject of a qualitative and quantitative study of interstitial lesions. Thirty of the 98 patients showed interstitial cell infiltration and/or fibrosis. The initial and final creatinine clearance (Ccr) values were significantly lower in these 30 patients than in the remaining cases. Hypertension and progressive cases were more frequent in the group with interstitial lesions. Histologically, the severity and activity of glomerular lesions and IgG deposition in tubular basement membranes were more severe in the interstitial disease group. On a quantitative analysis of interstitial volumes (IV) in 20 of the 30 patients, there were significant differences in delta IV between the two respective groups with Ccr values greater than 80 ml/min and with those less than 80 both at the initial and final observations (p less than 0.05, each). Further, renal function was significantly lower in 11 cases showing delta IV greater than 17%, than in 9 cases with less than this (p less than 0.01). However, no differences in delta IV were found between the two groups divided according to the degree of severity and activity of glomerular lesions. Further, there was no correlation between renal function, and the severity and activity of glomerular lesions in the 20 cases with interstitial lesions. These results indicate that quantitative analysis is a very useful tool in the evaluation of the functional and prognostic significance of interstitial alterations in lupus nephritis.