In vivo detection of deposition of radiolabeled lupus antikidney antibody and its inhibition by soluble antigen.

UNLABELLED This investigation in an animal model was designed to test the feasibility of using radiolabeled lupus antikidney antibody to show renal deposition in vivo and the ability to block this deposition with a binding peptide. METHODS BALB/c mice received injections of radiolabeled murine anti-DNA antibody, antibody with no DNA binding capability, and DNA antibody simultaneously with blocking peptide. RESULTS Significantly higher renal deposition of anti-DNA antibody than of antibody without DNA binding capability occurred in the animals at 48 h after injection (5.21% of the injected dose per gram of tissue versus 2.5%, P < 0.0004) and at 7-8 d after injection (1.44% versus 0.20%, P < 0.00004). The simultaneous injection of blocking peptide with anti-DNA binding antibody significantly reduced the renal deposition of the anti-DNA antibody at 48 h (1.53%, P < 0.00001) and at 7-8 d (0.64%, P < 0.0017). CONCLUSION This study showed the feasibility of using a radiolabeled antibody to evaluate deposition of anti-DNA antibody in the kidney and the successful use of a peptide to block antibody deposition-a strategy that may be useful for renal preservation in lupus. These data support the possibility of using antikidney-labeled antibodies to evaluate immunologic renal disease in vivo in humans.