Tubular basement membrane deposits in human renal allografts.

In 18 patients who received renal allografts, tubulo-interstitial lesions were studied, according to the types of rejection or the possible recurrence of primary disease. Immunofluorescent (IF) investigation revealed tubular basement membrane (TBM) deposits of IgG and/or C3 and sometimes other components of Complement. The pattern of these deposits was: "linear" in 3 cases, "granular" in 9 cases and "atypical" with linear and granular segments in 6 cases. The IF study of own kidneys of 3 patients, before the transplantation, revealed no TBM deposits. TBM deposits were accompanied by arterial wall deposits of IgM and/or C3 and sometimes C5 in 17 cases. Electron-microscopy study of renal tubules showed thickening, lamellation and/or deposits along the tubular basement membrane. The immunopathogenesis of these deposits was discussed.