Tubulo-interstitial disease in lupus nephritis. A morphometric study

Area of Science:

• Nephrology
• Immunology
• Pathology

Background:

• Lupus nephritis is characterized by immune complex deposition in the kidneys.
• The role of immune complex deposition in causing tubulo-interstitial damage in lupus nephritis remains unclear.

Purpose of the Study:

• To investigate the hypothesis that immune complex deposition mediates tubulo-interstitial damage in lupus nephritis.
• To correlate immune deposits with tubulo-interstitial injury markers.

Main Methods:

• Correlative immunofluorescence and morphometric study of 43 renal biopsies from patients with diffuse proliferative lupus glomerulonephritis.
• Quantification of mononuclear cell infiltrates (infiltrate index) and interstitial volume (interstitial index) using point-counting.
• Estimation of immunoglobulin deposits in the tubulo-interstitium.

Main Results:

• Interstitial cell infiltrates were present in 40/43 biopsies; tubulo-interstitial immune deposits were found in 29/43.
• A significant correlation was observed between interstitial volume and infiltrate index (r=0.553, P<0.001).
• No significant correlation was found between the extent of immune deposits and either interstitial index or infiltrate index.

Conclusions:

• The study does not support the hypothesis that immune deposits directly mediate tubulo-interstitial injury in lupus nephritis.
• Inflammatory cell infiltrates are suggested to be the primary mediators of tubulo-interstitial damage in this condition.