In situ formation of antigen-antibody complexes in the mouse glomerulus.

Intravenous administration of heat-aggregated bovine serum albumin (BSA) to mice resulted in localization of micro-particulate BSA in the mesangial region of the glomerulus. Subsequent intravenous administration of rabbit anti-BSA antibody at a time when no free antigen remained in the circulation produced localization of antibody and fixation of mouse complement within the glomerulus in a pattern corresponding to that of the heat-aggregated BSA. This apparent in situ formation of immune complexes in the glomerulus is similar to that of the classical Arthus phenomenon in the skin.