Clinicopathologic correlations in lupus nephritis in Lima, Peru

Background: We assessed whether immunohistologic markers for glomerular or tubulointerstitial injury might provide better correlations with ongoing re nal function and disease activity as compared with the WHO classification o r the NIH activity and chronicity indices in lupus nephritis. Methods: Thir ty-three patients with clinically defined systemic lupus underwent renal bi opsy over a 1-year period at Hospital Loayza in Lima, Peru. Biopsy specimen s were evaluated for macrophages, proliferating cells, alpha-actin expressi on, and type IV collagen deposition in both glomeruli and the tubulointerst itium and the results compared with the current WHO and NIH classifications in relation to the clinical presentation. Results: Patients with WHO class IV lupus nephritis were more likely to have lower serum complements, great er proteinuria and hematuria, and worse renal function. An elevated NIH act ivity index correlated with microhematuria, proteinuria, and impaired renal function, whereas an elevated chronicity index correlated with renal funct ion, hypertension, and microhematuria, but not with proteinuria. The presen ce of glomerular macrophages correlated with both glomerular alpha-actin ex pression and type IV collagen deposition, but did not correlate with renal function or proteinuria. In contrast, interstitial macrophages correlated n ot only with interstitial collagen deposition and myofibroblast accumulatio n, but also correlated with both renal function and the presence of nephrot ic syndrome. Conclusions: Both the WHO classification and the NIH activity/ chronicity indices correlate with clinical manifestations of lupus nephriti s. While glomerular macrophage accumulation correlates with mesangial cell activation (alpha-actin expression) and collagen deposition, and interstiti al macrophage accumulation correlates with interstitial fibroblast activati on and collagen deposition, only interstitial macrophages correlate with re nal function. Of particular interest will be future studies to determine wh ether these markers correlate With the prognosis. Copyright (C) 1999 S. Kar ger AG, Basel.