[Radiometric detection of nonvisualizable immunoprecipitates formed by hepatoma-associated hetero-organic renal antigens of 33P-phosphorylated fractions of non-histone chromatin proteins].

A study was made of the antigenic properties of nuclear nonhistone proteins (NHP) from rat tissue eluted with 0.4-0.5 M NaCl gradient on phosphocellulose at very low concentrations. 33P-labeled proteins were obtained by phosphorylation of NHP fractions in the presence of [gamma-33P] ATP. Some non-visual precipitates which appeared during the reaction of specific inhibition of precipitation in agarose gel of 33P-labeled NHP-fractions from rat solid hepatoma 27 cells or rat liver after single hepatocarcinogen diethylnitrosamine injection were detected by means of a calculable radiometric method, proposed by the authors. These precipitates appear only if the rabbit immune sera against NHP-DNA complexes of intact rat kidneys exhausted with liver NHP-antigens was used, never appearing in the case of kidney NHP-antigen exhaustion. Therefore the NHP-fractions prepared from "carcinogenic" liver and rat solid hepatoma cells which possess proper phosphoprotein kinase activity and form specific immune precipitates must be identified as hetero-organic antigens of kidney origin.