Two soluble antigens, BSA and KLH labeled with sulfanilate-35S, when injected intravenously into normal animals, were excreted in the urine to over 70% in 24 hr. Over the next 6 days, 25% more was excreted after which time only a trace could be detected. Much of the antigen remaining from the primary injection appeared in the urine following a secondary injection of the unlabeled protein carrier at 7 days after primary injection.
The antigen material found in the urine was quite heterogeneous with respect to physical properties and much of it was associated with RNA material as shown by chromatographic analyses. The main difference between the labeled material released following the primary and secondary injection was the higher degree of association of antigen material with nucleotide material after secondary injection as compared with primary injection. Further study is needed to distinguish qualitative from quantitative changes of the components, antigen and nucleic acid, and also the nature of their association. Possible similarities were found for the RNA-antigen material released from tissue after secondary injection of unlabeled antigen, and the material that was isolated previously from liver.