Complexes of 125I p30, a viral core polypeptide, and rat anti-p30 antibody, preformed in vitro, were injected into the heart of BN rats bearing Moloney sarcomas (MST) and of BN rats bearing an unrelated tumor or unexposed to tumor. Complexes were cleared from the circulation of MST-bearing rats more rapidly than from sera of controls and were almost completely eliminated after 30 hr. There was no relationship between rate of disappearance and size of tumor or levels of circulating complexes. Disappearance rates in rats with progressing and regressing tumors were similar. Uncomplexed labeled p30 was cleared from the circulation of tumor-bearing and control rats with kinetics similar to those of labeled complexes. Complexes were localized in the spleen of tumor-bearing and control rats, but much more in spleens of MST-bearing rats. No other tissues, including tumor, concentrated complexes, nor was there binding to peripheral blood and spleen cells. The data suggest that augmented clearance and sequestration were due to the formation of large insoluble complexes that were rapidly removed by the reticulo-endothelial system.
This is publication No. 1478, Scripps Clinic and Research Foundation, Department of Immunopathology, La Jolla, California 92037. This work was supported by a contract from the National Cancer Institute 1001-CB-43874); by Grant AI-07007 from the National Institutes of Health; by a contract from ERDA, No. E(04-3)779; and by a grant from the Biomedical Research Support Program, (RR05514).