Studies of reticuloendothelial function in the mouse with model immune complexes. II. Serum clearance, tissue uptake, and reticuloendothelial saturation in NZB/W mice.

We have extended the findings in the accompanying paper by characterizing the serum clearance and tissue uptake of model soluble immune complexes and the saturation of the reticuloendothelial system (RES) by these complexes in normal mice and in mice with murine lupus (NZB/W F1 females). Adult NZB/W or young C3H mice were injected with radiolabeled stable site-specifically cross-linked mouse anti-DNP oligomers as model immune complexes to probe RES function. Blood clearance and uptake by liver, spleen, and kidney were unimpaired in NZB/W mice. To determine if the RES exhibits partial saturation in the NZB/W mice, we deliberately induced a state of RES blockade with heat-aggregated human gamma-glubulin (HAG). With increasing doses of HAG (1 to 4 mg/20 g body weight) both strains similarly showed a progressive increase in RES saturation as measured by reduced liver uptake of model oligomers. Recovery from saturation was complete by 120 min in both strains. At maximal liver saturation there was only a small increase in oligomer uptake by kidney or spleen, the majority of complexes remaining within the circulation. Thus, RES capacity for handling soluble model immune complexes appears unimpaired in NZB/W mice.