Localization of Anti-Brain Radioantibodies in Rat Brain

Abstract

Summary The brain localization of intravenously (i.v.) and intracerebrally (i.c.) injected radioantibodies and normal radioglobulin in rats has been investigated. Cross-localizing antibodies, that remain in brain when i.c. injected but localize primarily in other normal tissue when i. v. injected, were used to test the concept that the blood-brain barrier to radioglobulin is in essence a dynamic equilibrium whose equilibrium constant favors the general circulation by several orders of magnitude. This concept was offered to explain the phenomenon that i.c. injected normal radioglobulin achieved the same general bodily distribution as did i. v. injected normal radioglobulin. Through passive transfer of 125I-labeled antibrain radioantibody, paired with 131I-labeled normal radioglobulin, in normal rats for 2 hr, and subsequent i.v. transfer of serum-borne radioglobulins to normal recipient rats for another 24 hr, a specific brain-localizing antibody was detected in minute but significant amounts. It was not determined whether the detected portion constituted the bulk of the specific entity or whether some was removed during the passive transfer.