The beta-glucuronidase release from macrophages activated by immune complexes of varying antigen/antibody ratio.

When unstimulated rat peritoneal macrophages are exposed in vitro to IC formed with BSA and specific rat anti-BSA IgG antibodies, an exocytosis of the lysosomal beta-G occurs. The maximal release of beta-G into the serum-free medium is induced, without cell lysis, by IC after a 6-h contact with the adherent cell population. This phenomenon is dose-dependent, and the percentage of beta-G in the medium is higher with IC in Ab excess than with other types of IC. In this homologous model (rat macrophages and rat antibodies) the Ag/Ab ratio of IC seems to represent an important factor of macrophage activation.