Effect of chemical modification of antigen on characteristics of immune complexes and their glomerular localization in the murine renal tissues.

In order to investigate the effect of chemical cationization of antigen on the glomerular localization of immune complexes (IC), the glomerular localization was studied in passive serum sickness nephritis of mice using IC composed of antigens with various pI values and antibody raised against the unmodified antigen. The chemical cationization of antigen altered the interaction between antigen and antibody: as the pI of the antigen became higher, the precipitating efficiency of antigen-antibody complexes became lower or zero. This phenomenon was due to a decrease in valence of the antigen and a decrease in avidity between the cationized antigen and antibody directed against unmodified antigen. Therefore, the size of IC composed of the antigens with higher pI became smaller. However, the IC appeared not to dissociate in vivo and in vitro where the pI of antigen was between 9.15 and 10.25. The pI of the IC made with cationic antigen was also above 9.5. In the animals given IC composed of the antigens with higher pI values, peripheral glomerular localization of IC was increased. In contrast, in the animals given IC composed of unmodified antigen, focal mesangial deposition of IC was seen.