[The effect of antigenic charges in the glomerular deposition of immune complexes in acute serum sickness nephritis in mice].

We examined the role of antigenic charge on the deposition of immune complexes (IC) in murine gloerulia Acute serum sickens nephritis was induced by injecting chemically modified cationic bovine serum albumin (cationic BSA). Controls were immunized with unmodified native BSA (native BSA), All mice were given a primary intraperitoneal immunization with 500 pg of the respective antigens plus Freund's complete adjuvant . After 14 days, we divided the mice into following three groups . The first group was bled and killed for the characterization of antisera and histologic study o Second group was injected intravenously with 200 pug of I-labeled each BSA and bled at 5 minutes for measuring the size of IC® Third group was killed at 15 minutes after the second injection for histologic study. In the former renal specimens , neither IC nor antigen was detected in all animals. After the challenge, mice immunized with cationic BSA showed capillary wall deposits of IgG, whereas those immunized with native BSA developed mesangial depositions of IgG . Antibody avidity values in cationic BSA group were significantly lower than those in native BSA group (P<0, 005). The sucrose density gradient ultracentrif ugation study showed that the size of IC in cationic BSA group was slightly larger than 7S. From the above results, we speculated that : 1) The IC depositions on the glomerular capillary walls result from circulating IC formation. 2) The IC composed of cationic BSA effectively binds to the polyanion layer of the glomerular basement membrane. 3) Chemically modified cationization alters the characteristics of BSA , thereby causing the formation of small sized IC.