Murine autoimmune interstitial nephritis and associated antigen: purification of a soluble tubular basement membrane antigen from mice kidneys.

A soluble tubular basement membrane (TBM) antigen has been purified from murine kidneys. The isolated fibers were trypsinized and subjected to zone electrophoresis, Sephadex G-200 gel filtration, and DEAE-cellulose chromatography eluted with linear NaCl concentration gradient while monitoring the TBM antigen activity with specific antihuman TBM antigen. The molecular weight of TBM antigen was estimated to be 30,000 daltons by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified TBM antigen gave a single precipitin line against the specific antiserum and cross-reacted with the TBM antigen similarly purified from other animals such as goat, guinea pig and also with human TBM antigen in an immunodiffusion plate. BALB/c, C3H/He and C57BL/6 mice were immunized twice at 2 weeks' interval with the TBM antigen and adjuvant. Histologically typical interstitial nephritis occurred in BALB/c mice, whereas no nephritis developed in other strains of mice. The inflammatory changes were characterized by intense mononuclear cell infiltration, tubular destruction, and interstitial and periglomerular fibrosis. The serum-stained basement membrane of normal tubules and Bowman's capsules, and no antiglomerular basement membrane activity was detectable in the serum by immunofluorescence. This system provides a simple and useful model in interstitial nephritis in mice produced with a purified TBM antigen.