The disappearance kinetics and glomerular deposition of small-latticed soluble immune complexes

The disappearance from circulation and the glomerular localization of human serum albumin (HSA) anti-HSA complexes made at fifty-fold antigen excess were examined in mice and compared with the same features of complexes made at five-fold antigen excess. Complexes prepared at fifty-fold antigen excess consisted principally of small-latticed complexes (Ag2Ab2 and Ag1Ab1) that persisted in the circulation after the initial rapid disappearance attributed to extravasation. The presence of small-latticed complexes in the circulation did not lead to glomerular localization of complexes during a 96 hr period. In contrast, when large-latticed soluble complexes, prepared at five-fold antigen excess, were injected, abundant glomerular deposits developed. These observations indicate that the lattice of circulating immune complexes must exceed the Ag2Ab2 structure in order for glomerular deposition to occur.