Evidence for a saturable clearance mechanism for 111In-labeled monoclonal antibodies

We have studied the dose effect of 111In-labeled HDP-1 on lung and liver uptake in rats. At low doses (much less than 25 micrograms) the lung/liver ratios are quite low. Higher doses result in dramatically increased ratios, suggesting that an uptake or metabolic process in the liver was becoming saturated. These results are compared with those previously obtained with 125I-labeled HDP-1.