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

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 black this deposition with a binding peptide. Meth ods: BALB/c mice received injections of radiolabeled murine anti-DNA antibo dy, antibody with no DNA binding capability, and DNA antibody simultaneousl y 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% ver sus 0.20%, P < 0.00004). The simultaneous injection of blocking peptide wit h anti-DNA binding antibody significantly reduced the renal deposition of t he 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 radiolabe led antibody to evaluate deposition of anti-DNA antibody in the kidney and the successful use of a peptide to block antibody deposition-a strategy tha t may be useful for renal preservation in lupus. These data support the pos sibility of using antikidney-labeled antibodies to evaluate immunologic ren al disease in vivo in humans.