A tentative biological model for the localization of radiolabelled antibody in tumor: the importance of immunoreactivity

The model is based on the following assumptions, some of which have preliminary support in experimental studies: 1. That the binding reaction between tumor antigen and antibody is the dominant biologic process for tumor uptake in vivo. 2. That the capillary membrane does not completely permit free exchange between blood and extra-cellular fluid (E.C.F.) for immune proteins of appreciable size. Instead, an equilibrium state is relatively rapidly established, at least for fragments in the Fab size range, but a concentration gradient exists between plasma and E.C.F. (author)